[syzbot] KASAN: use-after-free Read in put_pmu_ctx

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
git tree: bpf
console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

CPU: 0 PID: 8300 Comm: syz-executor287 Not tainted 6.1.0-syzkaller-09661-g13e3c7793e2f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
__lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
put_pmu_ctx kernel/events/core.c:4913 [inline]
put_pmu_ctx+0xad/0x390 kernel/events/core.c:4893
_free_event+0x3c5/0x13d0 kernel/events/core.c:5196
free_event+0x58/0xc0 kernel/events/core.c:5224
__do_sys_perf_event_open+0x66d/0x2980 kernel/events/core.c:12701
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3a2b1b3f29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4215df68 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f3a2b1b3f29
RDX: 0000000000000000 RSI: 0000000000002070 RDI: 0000000020000480
RBP: 0000000000000000 R08: 0000000000000008 R09: 0000000000000001
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000012a59
R13: 00007fff4215df7c R14: 00007fff4215df90 R15: 00007fff4215df80
</TASK>

Allocated by task 8300:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
alloc_perf_context kernel/events/core.c:4693 [inline]
find_get_context+0xcc/0x810 kernel/events/core.c:4763
__do_sys_perf_event_open+0x963/0x2980 kernel/events/core.c:12476
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5310:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0xaf/0x3b0 mm/slub.c:3800
rcu_do_batch kernel/rcu/tree.c:2244 [inline]
rcu_core+0x81f/0x1980 kernel/rcu/tree.c:2504
__do_softirq+0x1fb/0xadc kernel/softirq.c:571

Last potentially related work creation:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
__kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:488
__call_rcu_common.constprop.0+0x99/0x820 kernel/rcu/tree.c:2753
put_ctx kernel/events/core.c:1180 [inline]
put_ctx+0x116/0x1e0 kernel/events/core.c:1173
perf_event_exit_task_context kernel/events/core.c:13046 [inline]
perf_event_exit_task+0x556/0x760 kernel/events/core.c:13073
do_exit+0xb4d/0x2a30 kernel/exit.c:829
__do_sys_exit kernel/exit.c:917 [inline]
__se_sys_exit kernel/exit.c:915 [inline]
__x64_sys_exit+0x42/0x50 kernel/exit.c:915
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff8880237d6000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
512-byte region [ffff8880237d6000, ffff8880237d6200)

The buggy address belongs to the physical page:
page:ffffea00008df500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x237d4
head:ffffea00008df500 order:2 compound_mapcount:0 compound_pincount:0
anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012441c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2173, tgid 2173 (kworker/u4:3), ts 10211275854, free_ts 0
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4291
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5558
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1851 [inline]
allocate_slab+0x25f/0x350 mm/slub.c:1998
new_slab mm/slub.c:2051 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3193
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x1a4/0x430 mm/slub.c:3491
kmalloc_trace+0x26/0x60 mm/slab_common.c:1062
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
alloc_bprm+0x51/0x900 fs/exec.c:1510
kernel_execve+0xaf/0x500 fs/exec.c:1981
call_usermodehelper_exec_async+0x2e7/0x580 kernel/umh.c:113
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
page_owner free stack trace missing

Memory state around the buggy address:
ffff8880237d5f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880237d5f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880237d6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880237d6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880237d6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
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syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Hillf Danton]

On 19 Dec 2022 00:04:43 -0800

> syzbot found the following issue on:
>
> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000

Grab another hold on ctx to make it safe to lock ctx upon putting pmu.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- x/kernel/events/core.c
+++ y/kernel/events/core.c
@@ -4816,6 +4816,7 @@ find_get_pmu_context(struct pmu *pmu, st
raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);
@@ -4914,6 +4915,7 @@ static void put_pmu_ctx(struct perf_even
list_del_init(&epc->pmu_ctx_entry);
epc->ctx = NULL;
raw_spin_unlock_irqrestore(&ctx->lock, flags);
+ put_ctx(ctx);
}

WARN_ON_ONCE(!list_empty(&epc->pinned_active));
--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in __perf_event_task_sched_in

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925

Read of size 8 at addr ffff888070350018 by task syz-executor.0/5763

CPU: 0 PID: 5763 Comm: syz-executor.0 Not tainted 6.1.0-syzkaller-13139-gf9ff5644bcc0-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106

print_address_description mm/kasan/report.c:306 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:417
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517

__lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633

__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
perf_ctx_lock kernel/events/core.c:163 [inline]
perf_event_context_sched_in kernel/events/core.c:3925 [inline]
__perf_event_task_sched_in+0x19c/0x6c0 kernel/events/core.c:3976
perf_event_task_sched_in include/linux/perf_event.h:1328 [inline]
finish_task_switch.isra.0+0x5e5/0xc80 kernel/sched/core.c:5118
context_switch kernel/sched/core.c:5247 [inline]
__schedule+0xb92/0x5450 kernel/sched/core.c:6555
schedule+0xde/0x1b0 kernel/sched/core.c:6631
do_nanosleep+0x154/0x4f0 kernel/time/hrtimer.c:2044
hrtimer_nanosleep+0x1fd/0x4b0 kernel/time/hrtimer.c:2097
common_nsleep+0xa6/0xd0 kernel/time/posix-timers.c:1236
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1276 [inline]
__se_sys_clock_nanosleep kernel/time/posix-timers.c:1254 [inline]
__x64_sys_clock_nanosleep+0x2f8/0x430 kernel/time/posix-timers.c:1254

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7f6101eb0e01
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 aa e7 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 e3 e7 ff ff 48 8b 04 24 eb 97 66 2e 0f 1f
RSP: 002b:00007f6102cc20b0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00007f6101fabf80 RCX: 00007f6101eb0e01
RDX: 00007f6102cc20f0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f6101ee7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007fffb7c30faf R14: 00007f6102cc2300 R15: 0000000000022000
</TASK>

Allocated by task 5762:

kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
alloc_perf_context kernel/events/core.c:4693 [inline]
find_get_context+0xcc/0x810 kernel/events/core.c:4763

__do_sys_perf_event_open+0x963/0x2980 kernel/events/core.c:12478

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5759:

kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0xaf/0x3b0 mm/slub.c:3800
rcu_do_batch kernel/rcu/tree.c:2244 [inline]
rcu_core+0x81f/0x1980 kernel/rcu/tree.c:2504
__do_softirq+0x1fb/0xadc kernel/softirq.c:571

Last potentially related work creation:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
__kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:488
__call_rcu_common.constprop.0+0x99/0x820 kernel/rcu/tree.c:2753
put_ctx kernel/events/core.c:1180 [inline]
put_ctx+0x116/0x1e0 kernel/events/core.c:1173

put_pmu_ctx kernel/events/core.c:4918 [inline]
put_pmu_ctx+0x1db/0x390 kernel/events/core.c:4894
_free_event+0x3c5/0x13d0 kernel/events/core.c:5198
free_event+0x58/0xc0 kernel/events/core.c:5226
__do_sys_perf_event_open+0x66d/0x2980 kernel/events/core.c:12703

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888070350000

which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of

512-byte region [ffff888070350000, ffff888070350200)

The buggy address belongs to the physical page:

page:ffffea0001c0d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x70350
head:ffffea0001c0d400 order:2 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0

anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000010200 ffff888012041c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5565, tgid 5565 (syz-executor.1), ts 81058806266, free_ts 76174174820
prep_new_page mm/page_alloc.c:2531 [inline]
get_page_from_freelist+0x119c/0x2ce0 mm/page_alloc.c:4283
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549

alloc_pages+0x1aa/0x270 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1851 [inline]
allocate_slab+0x25f/0x350 mm/slub.c:1998
new_slab mm/slub.c:2051 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3193
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x1a4/0x430 mm/slub.c:3491

__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc_node_track_caller+0x4b/0xc0 mm/slab_common.c:988
kmalloc_reserve net/core/skbuff.c:492 [inline]
__alloc_skb+0xe9/0x310 net/core/skbuff.c:565
alloc_skb include/linux/skbuff.h:1270 [inline]
nlmsg_new include/net/netlink.h:1002 [inline]
mpls_netconf_notify_devconf+0x4a/0x110 net/mpls/af_mpls.c:1188
mpls_dev_sysctl_register+0x1fe/0x2d0 net/mpls/af_mpls.c:1425
mpls_add_dev net/mpls/af_mpls.c:1472 [inline]
mpls_dev_notify+0x450/0x930 net/mpls/af_mpls.c:1612
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1944
call_netdevice_notifiers_extack net/core/dev.c:1982 [inline]
call_netdevice_notifiers net/core/dev.c:1996 [inline]
register_netdevice+0xfb4/0x1640 net/core/dev.c:10078
rtnl_newlink_create net/core/rtnetlink.c:3409 [inline]
__rtnl_newlink+0x15a1/0x1840 net/core/rtnetlink.c:3624
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1446 [inline]
free_pcp_prepare+0x65c/0xc00 mm/page_alloc.c:1496
free_unref_page_prepare mm/page_alloc.c:3369 [inline]
free_unref_page+0x1d/0x490 mm/page_alloc.c:3464
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x192/0x220 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x66/0x90 mm/kasan/common.c:302
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slab.h:761 [inline]
slab_alloc_node mm/slub.c:3452 [inline]
slab_alloc mm/slub.c:3460 [inline]
__kmem_cache_alloc_lru mm/slub.c:3467 [inline]
kmem_cache_alloc+0x1e4/0x430 mm/slub.c:3476
vm_area_alloc+0x20/0x100 kernel/fork.c:458
mmap_region+0x44c/0x1dd0 mm/mmap.c:2601
do_mmap+0x831/0xf60 mm/mmap.c:1411
vm_mmap_pgoff+0x1af/0x280 mm/util.c:520
ksys_mmap_pgoff+0x7d/0x5a0 mm/mmap.c:1457

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:

ffff88807034ff00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
ffff88807034ff80: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>ffff888070350000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888070350080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888070350100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: f9ff5644 Merge tag 'hsi-for-6.2' of git://git.kernel.o..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=13ef5baf880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3263313469e7ca77

dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=158d1327880000

[Hillf Danton]

On 19 Dec 2022 00:04:43 -0800

> syzbot found the following issue on:
>
> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000

Grab another hold on ctx to make it safe to lock ctx upon putting pmu.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- x/kernel/events/core.c
+++ y/kernel/events/core.c

@@ -1172,7 +1172,7 @@ static void free_ctx(struct rcu_head *he

static void put_ctx(struct perf_event_context *ctx)
{
- if (refcount_dec_and_test(&ctx->refcount)) {
+ if (ctx && refcount_dec_and_test(&ctx->refcount)) {
if (ctx->parent_ctx)
put_ctx(ctx->parent_ctx);
if (ctx->task && ctx->task != TASK_TOMBSTONE)
@@ -3910,6 +3910,10 @@ static void perf_event_context_sched_in(
ctx = rcu_dereference(task->perf_event_ctxp);
if (!ctx)
goto rcu_unlock;
+ if (!refcount_inc_not_zero(&ctx->refcount)) {
+ ctx = NULL;
+ goto rcu_unlock;
+ }

if (cpuctx->task_ctx == ctx) {
perf_ctx_lock(cpuctx, ctx);
@@ -3957,6 +3961,7 @@ unlock:
perf_ctx_unlock(cpuctx, ctx);
rcu_unlock:
rcu_read_unlock();
+ put_ctx(ctx);
}

/*
@@ -4816,6 +4821,7 @@ find_get_pmu_context(struct pmu *pmu, st

raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);

@@ -4914,6 +4920,7 @@ static void put_pmu_ctx(struct perf_even

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5552 } 2685 jiffies s: 2817 root: 0x0/T
rcu: blocking rcu_node structures (internal RCU debug):

Tested on:

commit: f9ff5644 Merge tag 'hsi-for-6.2' of git://git.kernel.o..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

console output: https://syzkaller.appspot.com/x/log.txt?x=1337f01b880000

kernel config: https://syzkaller.appspot.com/x/.config?x=3263313469e7ca77
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=10acb79d880000

[Peter Zijlstra]

Does this help?

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e47914ac8732..bbff551783e1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12689,7 +12689,8 @@ SYSCALL_DEFINE5(perf_event_open,
return event_fd;

err_context:
- /* event->pmu_ctx freed by free_event() */
+ put_pmu_ctx(event->pmu_ctx);
+ event->pmu_ctx = NULL; /* _free_event() */
err_locked:
mutex_unlock(&ctx->mutex);
perf_unpin_context(ctx);

[s...@google.com]

Let's maybe try it this way:

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
13e3c7793e2f

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file kernel/events/core.c
patch: **** unexpected end of file in patch



Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=15861a9f880000

[s...@google.com]

Let's try again with hopefully a better formatted patch..

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file kernel/events/core.c
patch: **** unexpected end of file in patch



Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=1451cef0480000

[Peter Zijlstra]

On Mon, Dec 19, 2022 at 11:33:29AM -0800, s...@google.com wrote:
> On 12/19, Peter Zijlstra wrote:
> > On Mon, Dec 19, 2022 at 12:04:43AM -0800, syzbot wrote:

> > > HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of
> > https://git.kernel...
> > > git tree: bpf
> > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> > > kernel config:
> > https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> > > dashboard link:
> > https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f

^ so syzbot knows what tree and config were used to trigger the report,
then why:

> Let's maybe try it this way:
>
> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
> 13e3c7793e2f

do you have to repeat that again in order for it to test something?

[Peter Zijlstra]

On Mon, Dec 19, 2022 at 12:04:43AM -0800, syzbot wrote:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
> Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

OK, lemme try this.. still think having to repeat the tree it already
has is daft..

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git 13e3c7793e2f

diff --git a/kernel/events/core.c b/kernel/events/core.c
index eacc3702654d..7da593504c5b 100644

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5791 } 2673 jiffies s: 2805 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
console output: https://syzkaller.appspot.com/x/log.txt?x=121ea2e8480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=12d4ad4f880000

[Peter Zijlstra]

On Tue, Dec 20, 2022 at 12:43:25AM -0800, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> INFO: rcu detected stall in corrupted
>
> rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5791 } 2673 jiffies s: 2805 root: 0x0/T
> rcu: blocking rcu_node structures (internal RCU debug):

That is an entirely different issue methinks. Let me go write up a
Changelog for that thing and stuff it somewhere /urgent.

[Stanislav Fomichev]

On Tue, Dec 20, 2022 at 12:22 AM Peter Zijlstra <pet...@infradead.org> wrote:
>
> On Mon, Dec 19, 2022 at 11:33:29AM -0800, s...@google.com wrote:
> > On 12/19, Peter Zijlstra wrote:
> > > On Mon, Dec 19, 2022 at 12:04:43AM -0800, syzbot wrote:
>
> > > > HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of
> > > https://git.kernel...
> > > > git tree: bpf
> > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> > > > kernel config:
> > > https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> > > > dashboard link:
> > > https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
>
> ^ so syzbot knows what tree and config were used to trigger the report,
> then why:

I haven't used it before and wasn't sure whether it would take the
last commit from the branch of the one where it failed. Adding them
shouldn't hurt, right?

> > Let's maybe try it this way:
> >
> > #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
> > 13e3c7793e2f
>
> do you have to repeat that again in order for it to test something?

Yeah, I was trying to understand why it doesn't like my patch. It
seems I can retry with the patch attached which hopefully should fix
the possible formatting issue; let's see.

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5778 } 2673 jiffies s: 2773 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):

Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

console output: https://syzkaller.appspot.com/x/log.txt?x=12cb0e5d880000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f

compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=12df6a9b880000

[Chengming Zhou]

Tested-by: Chengming Zhou <zhouch...@bytedance.com>

While reviewing the code, I found perf_event_create_kernel_counter()
has the similar problem in the "err_pmu_ctx" error handling path:

CPU0 CPU1
perf_event_create_kernel_counter()
// inc ctx refcnt
find_get_context(task, event) (1)

// inc pmu_ctx refcnt
pmu_ctx = find_get_pmu_context()

event->pmu_ctx = pmu_ctx
...
goto err_pmu_ctx:
// dec pmu_ctx refcnt
put_pmu_ctx(pmu_ctx) (2)

mutex_unlock(&ctx->mutex)
// dec ctx refcnt
put_ctx(ctx)
perf_event_exit_task_context()
mutex_lock()
mutex_unlock()
// last refcnt put
put_ctx()
free_event(event)
if (event->pmu_ctx) // True
put_pmu_ctx() (3)
// will access freed pmu_ctx or ctx

if (event->ctx) // False
put_ctx()

(3) has UAF problem since the pmu_ctx maybe freed in (2), so also
should have "event->pmu_ctx = NULL;" in (2).

[Peter Zijlstra]

On Wed, Dec 21, 2022 at 10:42:39AM +0800, Chengming Zhou wrote:

> > Does this help?
> >
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index e47914ac8732..bbff551783e1 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -12689,7 +12689,8 @@ SYSCALL_DEFINE5(perf_event_open,
> > return event_fd;
> >
> > err_context:
> > - /* event->pmu_ctx freed by free_event() */
> > + put_pmu_ctx(event->pmu_ctx);
> > + event->pmu_ctx = NULL; /* _free_event() */
> > err_locked:
> > mutex_unlock(&ctx->mutex);
> > perf_unpin_context(ctx);
>
> Tested-by: Chengming Zhou <zhouch...@bytedance.com>
>
> While reviewing the code, I found perf_event_create_kernel_counter()
> has the similar problem in the "err_pmu_ctx" error handling path:

Right you are, updated the patch, thanks!

This doesn't look right; iirc you can hit this without concurrency,
something like so:


// note that when getting here, we've not passed
// perf_install_in_context() and event->ctx == NULL.
err_pmu_ctx:
put_pmu_ctx();
put_ctx(); // last, actually frees ctx
..
err_alloc:
free_event()
_free_event()
if (event->pmu_ctx) // true, because we forgot to clear
put_pmu_ctx() // hits 0 because double put
// goes and touch epc->ctx and UaF

[Chengming Zhou]

Right, pmu_ctx UaF can hit without concurrency.

But ctx has been created with refcnt == 1, which referenced by the task,
so the last refcnt put must be in perf_event_exit_task_context().

Maybe we can improve this, don't let ctx referenced by the task? Then ctx
can be freed when all perf_events are removed, instead of having to wait
for the task to exit. Maybe I missed something...

>
>
> // note that when getting here, we've not passed
> // perf_install_in_context() and event->ctx == NULL.
> err_pmu_ctx:
> put_pmu_ctx();
> put_ctx(); // last, actually frees ctx

This put_ctx() dec refcnt from 2 to 1, perf_event_exit_task_context()
will put the last refcnt and free it.

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800

> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4816,6 +4816,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,

raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);

@@ -4862,6 +4863,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,

list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;

+ get_ctx(&ctx);

found_epc:
if (task_ctx_data && !epc->task_ctx_data) {
@@ -4913,6 +4915,7 @@ static void put_pmu_ctx(struct perf_event_pmu_context *epc)
raw_spin_lock_irqsave(&ctx->lock, flags);

list_del_init(&epc->pmu_ctx_entry);
epc->ctx = NULL;

+ put_ctx(ctx);
raw_spin_unlock_irqrestore(&ctx->lock, flags);
}

--
2.37.2

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

kernel/events/core.c:4866:16: error: passing argument 1 of 'get_ctx' from incompatible pointer type [-Werror=incompatible-pointer-types]


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=143c1ada480000

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800

> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4816,6 +4816,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);
@@ -4862,6 +4863,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,

list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;

+ get_ctx(ctx);

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5783 } 2639 jiffies s: 2817 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
console output: https://syzkaller.appspot.com/x/log.txt?x=109c3fb8480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=12624392480000

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800

> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

@@ -4816,6 +4816,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);
@@ -4862,6 +4863,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,

list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);

found_epc:
if (task_ctx_data && !epc->task_ctx_data) {

@@ -4914,6 +4916,7 @@ static void put_pmu_ctx(struct perf_event_pmu_context *epc)

list_del_init(&epc->pmu_ctx_entry);
epc->ctx = NULL;

raw_spin_unlock_irqrestore(&ctx->lock, flags);
+ put_ctx(ctx);
}

WARN_ON_ONCE(!list_empty(&epc->pinned_active));
--

2.37.2

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5779 } 2688 jiffies s: 2785 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

console output: https://syzkaller.appspot.com/x/log.txt?x=13e0f348480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800

> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

@@ -13021,7 +13021,6 @@ static void perf_event_exit_task_context(struct task_struct *child)
* and mark the context dead.
*/
RCU_INIT_POINTER(child->perf_event_ctxp, NULL);
- put_ctx(child_ctx); /* cannot be last */
WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
put_task_struct(current); /* cannot be last */

--
2.37.2

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

KASAN: use-after-free Read in put_pmu_ctx

==================================================================

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925

Read of size 8 at addr ffff88806a928018 by task syz-executor.0/6370

CPU: 1 PID: 6370 Comm: syz-executor.0 Not tainted 6.1.0-syzkaller-08487-g13e3c7793e2f #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
__lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
put_pmu_ctx kernel/events/core.c:4913 [inline]
put_pmu_ctx+0xad/0x390 kernel/events/core.c:4893
_free_event+0x3c5/0x13d0 kernel/events/core.c:5196
free_event+0x58/0xc0 kernel/events/core.c:5224
__do_sys_perf_event_open+0x66d/0x2980 kernel/events/core.c:12701
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7f8965a8c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f896670b168 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f8965babf80 RCX: 00007f8965a8c0d9
RDX: 0000000000000000 RSI: 0000000000000035 RDI: 0000000020000480
RBP: 00007f8965ae7ae9 R08: 0000000000000008 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc4bcd92af R14: 00007f896670b300 R15: 0000000000022000
</TASK>

Allocated by task 6370:

kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
alloc_perf_context kernel/events/core.c:4693 [inline]
find_get_context+0xcc/0x810 kernel/events/core.c:4763

__do_sys_perf_event_open+0x963/0x2980 kernel/events/core.c:12476

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 21:

kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0xaf/0x3b0 mm/slub.c:3800
rcu_do_batch kernel/rcu/tree.c:2244 [inline]
rcu_core+0x81f/0x1980 kernel/rcu/tree.c:2504
__do_softirq+0x1fb/0xadc kernel/softirq.c:571

Last potentially related work creation:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
__kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:488
__call_rcu_common.constprop.0+0x99/0x820 kernel/rcu/tree.c:2753
put_ctx kernel/events/core.c:1180 [inline]
put_ctx+0x116/0x1e0 kernel/events/core.c:1173

perf_event_exit_task_context kernel/events/core.c:13046 [inline]
perf_event_exit_task+0x556/0x760 kernel/events/core.c:13073
do_exit+0xb4d/0x2a30 kernel/exit.c:829
__do_sys_exit kernel/exit.c:917 [inline]
__se_sys_exit kernel/exit.c:915 [inline]
__x64_sys_exit+0x42/0x50 kernel/exit.c:915

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88806a928000

which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of

512-byte region [ffff88806a928000, ffff88806a928200)

The buggy address belongs to the physical page:

page:ffffea0001aa4a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6a928
head:ffffea0001aa4a00 order:2 compound_mapcount:0 compound_pincount:0

anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000010200 ffff888012441c80 0000000000000000 dead000000000001

raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5786, tgid 5786 (syz-executor.1), ts 81977815415, free_ts 12951487418
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4291
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5558

alloc_pages+0x1aa/0x270 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1851 [inline]
allocate_slab+0x25f/0x350 mm/slub.c:1998
new_slab mm/slub.c:2051 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3193
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x1a4/0x430 mm/slub.c:3491
__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc_node_track_caller+0x4b/0xc0 mm/slab_common.c:988
kmalloc_reserve net/core/skbuff.c:492 [inline]
__alloc_skb+0xe9/0x310 net/core/skbuff.c:565
alloc_skb include/linux/skbuff.h:1270 [inline]

alloc_uevent_skb+0x7b/0x210 lib/kobject_uevent.c:290
uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline]
kobject_uevent_net_broadcast lib/kobject_uevent.c:412 [inline]
kobject_uevent_env+0x10f3/0x1620 lib/kobject_uevent.c:593
device_add+0xb76/0x1e90 drivers/base/core.c:3498
netdev_register_kobject+0x185/0x400 net/core/net-sysfs.c:2015
register_netdevice+0xd77/0x1640 net/core/dev.c:10045
nsim_init_netdevsim drivers/net/netdevsim/netdev.c:308 [inline]
nsim_create+0x437/0x5c0 drivers/net/netdevsim/netdev.c:357
__nsim_dev_port_add+0x2de/0x890 drivers/net/netdevsim/dev.c:1393

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]

free_pages_prepare mm/page_alloc.c:1459 [inline]
free_pcp_prepare+0x65c/0xd90 mm/page_alloc.c:1509
free_unref_page_prepare mm/page_alloc.c:3387 [inline]
free_unref_page+0x1d/0x4d0 mm/page_alloc.c:3483
free_contig_range+0xb5/0x180 mm/page_alloc.c:9496
destroy_args+0xa8/0x64c mm/debug_vm_pgtable.c:1031
debug_vm_pgtable+0x2958/0x29e9 mm/debug_vm_pgtable.c:1354
do_one_initcall+0x141/0x790 init/main.c:1306
do_initcall_level init/main.c:1379 [inline]
do_initcalls init/main.c:1395 [inline]
do_basic_setup init/main.c:1414 [inline]
kernel_init_freeable+0x6f9/0x782 init/main.c:1634
kernel_init+0x1e/0x1d0 init/main.c:1522
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Memory state around the buggy address:

ffff88806a927f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88806a927f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806a928000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88806a928080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88806a928100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

console output: https://syzkaller.appspot.com/x/log.txt?x=11952058480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5789 } 2632 jiffies s: 2853 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):

Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

console output: https://syzkaller.appspot.com/x/log.txt?x=172ac884480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=1032709a480000

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5764 } 2644 jiffies s: 2869 root: 0x0/T

rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 13e3c779 Merge tag 'for-netdev' of https://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

console output: https://syzkaller.appspot.com/x/log.txt?x=11994c52480000

kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=14a27fb2480000

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800

> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000

> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:

BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925

Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12690,6 +12690,8 @@ SYSCALL_DEFINE5(perf_event_open,

err_context:

/* event->pmu_ctx freed by free_event() */
+ put_pmu_ctx(event->pmu_ctx);
+ event->pmu_ctx = NULL;

err_locked:
mutex_unlock(&ctx->mutex);
perf_unpin_context(ctx);
@@ -12802,6 +12804,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,

err_pmu_ctx:
put_pmu_ctx(pmu_ctx);

+ event->pmu_ctx = NULL;

err_unlock:
mutex_unlock(&ctx->mutex);
perf_unpin_context(ctx);
--
2.37.2

[ead...@sina.com]

From: Edward Adam Davis <ead...@sina.com>

On Mon, 19 Dec 2022 00:04:43 -0800
> HEAD commit: 13e3c7793e2f Merge tag 'for-netdev' of https://git.kernel...
> git tree: bpf
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df7e0480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b0e91ad4b5f69c47
> dashboard link: https://syzkaller.appspot.com/bug?extid=b8e8c01c8ade4fe6e48f
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e87100480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ceeb13880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/373a99daa295/disk-13e3c779.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7fa71ed0fe17/vmlinux-13e3c779.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2842ad5c698b/bzImage-13e3c779.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b8e8c0...@syzkaller.appspotmail.com

syzbot report:
BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff8880237d6018 by task syz-executor287/8300

Test 13e3c7793e2f uaf.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 13e3c7793e2f

--- a/kernel/events/core.c
+++ b/kernel/events/core.c

@@ -4816,6 +4816,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
raw_spin_lock_irq(&ctx->lock);
list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);
raw_spin_unlock_irq(&ctx->lock);
} else {
WARN_ON_ONCE(epc->ctx != ctx);
@@ -4862,6 +4863,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,

list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
epc->ctx = ctx;
+ get_ctx(ctx);

found_epc:
if (task_ctx_data && !epc->task_ctx_data) {
@@ -4914,6 +4916,7 @@ static void put_pmu_ctx(struct perf_event_pmu_context *epc)
list_del_init(&epc->pmu_ctx_entry);
epc->ctx = NULL;
raw_spin_unlock_irqrestore(&ctx->lock, flags);
+ put_ctx(ctx);
}

WARN_ON_ONCE(!list_empty(&epc->pinned_active));

@@ -13021,7 +13024,6 @@ static void perf_event_exit_task_context(struct task_struct *child)