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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c9f8d73645b6 net: mtk_eth_soc: enable flow offload support..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12f9af53880000
kernel config: https://syzkaller.appspot.com/x/.config?x=c608c21151db14f2
dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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=17fedb97880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1749f597880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bf270f71d81b/disk-c9f8d736.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9df5873e74c3/vmlinux-c9f8d736.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4db90f01e6d3/bzImage-c9f8d736.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3538a6...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in rxrpc_local_cmp_key net/rxrpc/local_object.c:53 [inline]
BUG: KASAN: use-after-free in rxrpc_lookup_local+0xdcf/0xfb0 net/rxrpc/local_object.c:224
Read of size 2 at addr ffff888022b3521c by task syz-executor112/3641

CPU: 0 PID: 3641 Comm: syz-executor112 Not tainted 6.1.0-rc7-syzkaller-01810-gc9f8d73645b6 #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
rxrpc_local_cmp_key net/rxrpc/local_object.c:53 [inline]
rxrpc_lookup_local+0xdcf/0xfb0 net/rxrpc/local_object.c:224
rxrpc_bind+0x35e/0x5c0 net/rxrpc/af_rxrpc.c:150
__sys_bind+0x1ed/0x260 net/socket.c:1776
__do_sys_bind net/socket.c:1787 [inline]
__se_sys_bind net/socket.c:1785 [inline]
__x64_sys_bind+0x73/0xb0 net/socket.c:1785
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: 0033:0x7f9f1c5edd39
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:00007ffdd21e4598 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 000000000000dd76 RCX: 00007f9f1c5edd39
RDX: 0000000000000024 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffdd21e4738 R09: 00007ffdd21e4738
R10: 00007ffdd21e4010 R11: 0000000000000246 R12: 00007ffdd21e45ac
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
</TASK>

Allocated by task 3634:
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:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:93 [inline]
rxrpc_lookup_local+0x4d9/0xfb0 net/rxrpc/local_object.c:249
rxrpc_bind+0x35e/0x5c0 net/rxrpc/af_rxrpc.c:150
__sys_bind+0x1ed/0x260 net/socket.c:1776
__do_sys_bind net/socket.c:1787 [inline]
__se_sys_bind net/socket.c:1785 [inline]
__x64_sys_bind+0x73/0xb0 net/socket.c:1785
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 3624:
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:511
____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:1724 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1750
slab_free mm/slub.c:3661 [inline]
__kmem_cache_free+0xaf/0x3b0 mm/slub.c:3674
rcu_do_batch kernel/rcu/tree.c:2250 [inline]
rcu_core+0x81f/0x1980 kernel/rcu/tree.c:2510
__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:481
call_rcu+0x9d/0x820 kernel/rcu/tree.c:2798
rxrpc_put_local.part.0+0x128/0x170 net/rxrpc/local_object.c:332
rxrpc_put_local+0x25/0x30 net/rxrpc/local_object.c:324
rxrpc_release_sock net/rxrpc/af_rxrpc.c:888 [inline]
rxrpc_release+0x237/0x550 net/rxrpc/af_rxrpc.c:914
__sock_release+0xcd/0x280 net/socket.c:650
sock_close+0x1c/0x20 net/socket.c:1365
__fput+0x27c/0xa90 fs/file_table.c:320
task_work_run+0x16f/0x270 kernel/task_work.c:179
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xb3d/0x2a30 kernel/exit.c:820
do_group_exit+0xd4/0x2a0 kernel/exit.c:950
__do_sys_exit_group kernel/exit.c:961 [inline]
__se_sys_exit_group kernel/exit.c:959 [inline]
__x64_sys_exit_group+0x3e/0x50 kernel/exit.c:959
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 ffff888022b35000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 540 bytes inside of
1024-byte region [ffff888022b35000, ffff888022b35400)

The buggy address belongs to the physical page:
page:ffffea00008acc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x22b30
head:ffffea00008acc00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888012041dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3624, tgid 3624 (sshd), ts 56650444929, free_ts 56632976403
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:1794 [inline]
allocate_slab+0x213/0x300 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3180
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279
slab_alloc_node mm/slub.c:3364 [inline]
__kmem_cache_alloc_node+0x199/0x3e0 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node_track_caller+0x4b/0xc0 mm/slab_common.c:975
kmalloc_reserve net/core/skbuff.c:438 [inline]
__alloc_skb+0xe9/0x310 net/core/skbuff.c:511
alloc_skb_fclone include/linux/skbuff.h:1319 [inline]
tcp_stream_alloc_skb+0x3c/0x580 net/ipv4/tcp.c:862
tcp_sendmsg_locked+0xc4f/0x2960 net/ipv4/tcp.c:1325
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1483
inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:827
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
sock_write_iter+0x295/0x3d0 net/socket.c:1108
call_write_iter include/linux/fs.h:2199 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9ed/0xdd0 fs/read_write.c:584
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
__unfreeze_partials+0x17c/0x1a0 mm/slub.c:2586
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x184/0x210 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:737 [inline]
slab_alloc_node mm/slub.c:3398 [inline]
__kmem_cache_alloc_node+0x2e2/0x3e0 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc+0x4a/0xd0 mm/slab_common.c:968
kmalloc include/linux/slab.h:558 [inline]
tomoyo_add_entry security/tomoyo/common.c:2022 [inline]
tomoyo_supervisor+0xb60/0xf10 security/tomoyo/common.c:2094
tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
tomoyo_env_perm+0x183/0x200 security/tomoyo/environ.c:63
tomoyo_environ security/tomoyo/domain.c:672 [inline]
tomoyo_find_next_domain+0x13d2/0x1f80 security/tomoyo/domain.c:879
tomoyo_bprm_check_security security/tomoyo/tomoyo.c:101 [inline]
tomoyo_bprm_check_security+0x125/0x1b0 security/tomoyo/tomoyo.c:91
security_bprm_check+0x49/0xb0 security/security.c:869
search_binary_handler fs/exec.c:1715 [inline]
exec_binprm fs/exec.c:1768 [inline]
bprm_execve fs/exec.c:1837 [inline]
bprm_execve+0x732/0x19f0 fs/exec.c:1799
do_execveat_common+0x724/0x890 fs/exec.c:1942
do_execve fs/exec.c:2016 [inline]
__do_sys_execve fs/exec.c:2092 [inline]
__se_sys_execve fs/exec.c:2087 [inline]
__x64_sys_execve+0x93/0xc0 fs/exec.c:2087

Memory state around the buggy address:
ffff888022b35100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888022b35180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888022b35200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888022b35280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888022b35300: 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:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[David Howells]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master

rxrpc: Fix NULL deref in rxrpc_unuse_local()

Fix rxrpc_unuse_local() to get the debug_id *after* checking to see if
local is NULL.

Fixes: a2cf3264f331 ("rxrpc: Fold __rxrpc_unuse_local() into rxrpc_unuse_local()")
Reported-by: syzbot+3538a6...@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhow...@redhat.com>
cc: Marc Dionne <marc....@auristor.com>
cc: linu...@lists.infradead.org
---
net/rxrpc/local_object.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)


diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 44222923c0d1..24ee585d9aaf 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -357,10 +357,11 @@ struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local,
*/
void rxrpc_unuse_local(struct rxrpc_local *local, enum rxrpc_local_trace why)
{
- unsigned int debug_id = local->debug_id;
+ unsigned int debug_id;
int r, u;

if (local) {
+ debug_id = local->debug_id;
r = refcount_read(&local->ref);
u = atomic_dec_return(&local->active_users);
trace_rxrpc_local(debug_id, why, r, u);

[Hillf Danton]

On 06 Dec 2022 08:34:35 -0800

> syzbot found the following issue on:
>
> HEAD commit: c9f8d73645b6 net: mtk_eth_soc: enable flow offload support..
> git tree: net-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1749f597880000

rxrpc_release_sock rxrpc_bind
rxrpc_put_local rxrpc_lookup_local
call_rcu mutex_lock(&rxnet->local_mutex);
kfree
hlist_for_each(cursor, &rxnet->local_endpoints) {
local = hlist_entry(cursor, struct rxrpc_local, link);
uaf <-- diff = rxrpc_local_cmp_key(local, srx);

To fix the uaf, destroy local in workqueue because of hlist_del under mutex.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git c9f8d73645b6

--- x/net/rxrpc/ar-internal.h
+++ y/net/rxrpc/ar-internal.h
@@ -299,6 +299,7 @@ struct rxrpc_local {
bool dead;
bool service_closed; /* Service socket closed */
struct sockaddr_rxrpc srx; /* local address */
+ struct work_struct destroy_work;
};

/*
--- x/net/rxrpc/local_object.c
+++ y/net/rxrpc/local_object.c
@@ -312,6 +312,20 @@ struct rxrpc_local *rxrpc_get_local_mayb
return NULL;
}

+static void rxrpc_local_destroy_workfn(struct work_struct *w)
+{
+ struct rxrpc_local *local = container_of(w, struct rxrpc_local, destroy_work);
+ struct rxrpc_net *rxnet = local->rxnet;
+
+ mutex_lock(&rxnet->local_mutex);
+ if (!hlist_unhashed(&local->link))
+ hlist_del_init_rcu(&local->link);
+ mutex_unlock(&rxnet->local_mutex);
+
+ rxrpc_see_local(local, rxrpc_local_free);
+ kfree(local);
+}
+
/*
* Drop a ref on a local endpoint.
*/
@@ -328,8 +342,10 @@ void rxrpc_put_local(struct rxrpc_local
dead = __refcount_dec_and_test(&local->ref, &r);
trace_rxrpc_local(debug_id, why, r, u);

- if (dead)
- call_rcu(&local->rcu, rxrpc_local_rcu);
+ if (!dead)
+ return;
+ INIT_WORK(&local->destroy_work, rxrpc_local_destroy_workfn);
+ schedule_work(&local->destroy_work);
}
}

--

[syzbot]

Hello,

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

==================================================================
BUG: KASAN: use-after-free in rxrpc_local_cmp_key net/rxrpc/local_object.c:53 [inline]
BUG: KASAN: use-after-free in rxrpc_lookup_local+0xdcf/0xfb0 net/rxrpc/local_object.c:224

Read of size 2 at addr ffff88807652021c by task syz-executor.0/4166

CPU: 0 PID: 4166 Comm: syz-executor.0 Not tainted 6.1.0-rc7-syzkaller-01816-gb93884eea26f-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:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
rxrpc_local_cmp_key net/rxrpc/local_object.c:53 [inline]
rxrpc_lookup_local+0xdcf/0xfb0 net/rxrpc/local_object.c:224
rxrpc_bind+0x35e/0x5c0 net/rxrpc/af_rxrpc.c:150
__sys_bind+0x1ed/0x260 net/socket.c:1776
__do_sys_bind net/socket.c:1787 [inline]
__se_sys_bind net/socket.c:1785 [inline]
__x64_sys_bind+0x73/0xb0 net/socket.c:1785
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: 0033:0x7f7809a8c0d9
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:00007f780a709168 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00007f7809babf80 RCX: 00007f7809a8c0d9

RDX: 0000000000000024 RSI: 0000000020000040 RDI: 0000000000000003

RBP: 00007f7809ae7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff714ad7bf R14: 00007f780a709300 R15: 0000000000022000
</TASK>

Allocated by task 4161:

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:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:93 [inline]
rxrpc_lookup_local+0x4d9/0xfb0 net/rxrpc/local_object.c:249
rxrpc_bind+0x35e/0x5c0 net/rxrpc/af_rxrpc.c:150
__sys_bind+0x1ed/0x260 net/socket.c:1776
__do_sys_bind net/socket.c:1787 [inline]
__se_sys_bind net/socket.c:1785 [inline]
__x64_sys_bind+0x73/0xb0 net/socket.c:1785
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:

resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888076520000

which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 540 bytes inside of

1024-byte region [ffff888076520000, ffff888076520400)

The buggy address belongs to the physical page:

page:ffffea0001d94800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x76520
head:ffffea0001d94800 order:3 compound_mapcount:0 compound_pincount:0

flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888012041dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4161, tgid 4160 (syz-executor.0), ts 79477960432, free_ts 79222719756

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:1794 [inline]
allocate_slab+0x213/0x300 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3180
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279
slab_alloc_node mm/slub.c:3364 [inline]
__kmem_cache_alloc_node+0x199/0x3e0 mm/slub.c:3437

kmalloc_trace+0x26/0x60 mm/slab_common.c:1045

kmalloc include/linux/slab.h:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:93 [inline]
rxrpc_lookup_local+0x4d9/0xfb0 net/rxrpc/local_object.c:249
rxrpc_bind+0x35e/0x5c0 net/rxrpc/af_rxrpc.c:150
__sys_bind+0x1ed/0x260 net/socket.c:1776
__do_sys_bind net/socket.c:1787 [inline]
__se_sys_bind net/socket.c:1785 [inline]
__x64_sys_bind+0x73/0xb0 net/socket.c:1785
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

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
__unfreeze_partials+0x17c/0x1a0 mm/slub.c:2586
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x184/0x210 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:737 [inline]
slab_alloc_node mm/slub.c:3398 [inline]
__kmem_cache_alloc_node+0x2e2/0x3e0 mm/slub.c:3437

kmalloc_trace+0x26/0x60 mm/slab_common.c:1045
kmalloc include/linux/slab.h:553 [inline]
netdevice_queue_work drivers/infiniband/core/roce_gid_mgmt.c:643 [inline]
netdevice_event+0x368/0x8f0 drivers/infiniband/core/roce_gid_mgmt.c:802
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]
dev_set_mac_address+0x2d7/0x3e0 net/core/dev.c:8791
dev_set_mac_address_user+0x31/0x50 net/core/dev.c:8805
do_setlink+0x18c4/0x3bb0 net/core/rtnetlink.c:2775
__rtnl_newlink+0xd69/0x1840 net/core/rtnetlink.c:3590
rtnl_newlink+0x68/0xa0 net/core/rtnetlink.c:3637

Memory state around the buggy address:

ffff888076520100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888076520180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888076520200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888076520280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888076520300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: b93884ee net/ncsi: Silence runtime memcpy() false posi..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=144320db880000

kernel config: https://syzkaller.appspot.com/x/.config?x=c608c21151db14f2
dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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=145e216b880000

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+3538a6...@syzkaller.appspotmail.com

Tested on:

commit: c9f8d736 net: mtk_eth_soc: enable flow offload support..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1205f597880000

kernel config: https://syzkaller.appspot.com/x/.config?x=c608c21151db14f2
dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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=13c7a51d880000

Note: testing is done by a robot and is best-effort only.

[David Howells]

Hillf Danton <hda...@sina.com> wrote:

> To fix the uaf, destroy local in workqueue because of hlist_del under mutex.

Hmmm... That can't be the whole explanation. As you say, the hlist_del is
done under the mutex in rxrpc_destroy_local() - the same as the
hlist_add/hlist_replace and the search in rxrpc_lookup_local().

There should be no need to bump it off to a worker thread - the destruction is
in process context already - and doing the destruction not in the I/O thread
violates other assumptions, so I'm not convinced this patch is a valid fix.

I wonder if, under some circumstances, the I/O thread is managing to start and
destroy itself *before* rxrpc_lookup_local() adds itself to the
local_endpoints list. Possibly I should offload the add to the I/O thread and
use a completion to wait for it to set up.

David

[Hillf Danton]

On 07 Dec 2022 11:57:48 +0000 David Howells <dhow...@redhat.com>

> Hillf Danton <hda...@sina.com> wrote:
>
> > To fix the uaf, destroy local in workqueue because of hlist_del under mutex.
>
> Hmmm... That can't be the whole explanation. As you say, the hlist_del is
> done under the mutex in rxrpc_destroy_local() - the same as the
> hlist_add/hlist_replace and the search in rxrpc_lookup_local().

The uaf is simple and due to local ep freed without being deleted from
rxnet->local_endpoints while the list walker in rxrpc_lookup_local() stumbles
on it. rxrpc_destroy_local() is irrelevant as per the syzbot report.

>
> There should be no need to bump it off to a worker thread - the destruction is
> in process context already - and doing the destruction not in the I/O thread
> violates other assumptions, so I'm not convinced this patch is a valid fix.

It is freed in rcu context where taking rxnet->local_mutex for hlist_del
is a no go, so workqueue was proposed. I am open to any fix other than WQ.

>
> I wonder if, under some circumstances, the I/O thread is managing to start and
> destroy itself *before* rxrpc_lookup_local() adds itself to the
> local_endpoints list. Possibly I should offload the add to the I/O thread and
> use a completion to wait for it to set up.

Dunno what you are talking about here, given back traces in the report.

[David Howells]

Hillf Danton <hda...@sina.com> wrote:

> > Hmmm... That can't be the whole explanation. As you say, the hlist_del is
> > done under the mutex in rxrpc_destroy_local() - the same as the
> > hlist_add/hlist_replace and the search in rxrpc_lookup_local().
>
> The uaf is simple and due to local ep freed without being deleted from
> rxnet->local_endpoints while the list walker in rxrpc_lookup_local() stumbles
> on it. rxrpc_destroy_local() is irrelevant as per the syzbot report.

No, that's not the explanation. We can't get that far unless the I/O thread
got started - kthread_run() has to wait for the task_struct pointer to become
available - and the I/O thread should remove the link before it exits and
before the rxrpc_local object is deallocated.

I've tracked the problem down. It's due to kthread(), specifically this bit:

preempt_disable();
complete(done);
schedule_preempt_disabled();
preempt_enable();

ret = -EINTR;
if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
cgroup_kthread_ready();
__kthread_parkme(self);
ret = threadfn(data);
}

So the complete() is done before we've decided if we're going to call
threadfn() or return an error. This permits kthread_run() to resume before
we've checked KTHREAD_SHOULD_STOP - thus if kthread_stop() is called quickly
enough by the rxrpc socket being released, kthread() skips calling threadfn(),
but kthread_run() returns success.

The fact that the thread didn't start doesn't get seen until kthread_stop() is
called.

I think the above code needs rearranging slightly. KTHREAD_SHOULD_STOP should
be tested and, if needed EINTR set, *before* complete(done). That way
kthread_run() will return -EINTR in this case.

David

[David Howells]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master

diff --git a/kernel/kthread.c b/kernel/kthread.c
index f97fd01a2932..1335c89c6225 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -336,7 +336,6 @@ static int kthread(void *_create)
void *data = create->data;
struct completion *done;
struct kthread *self;
- int ret;

self = to_kthread(current);

@@ -365,17 +364,20 @@ static int kthread(void *_create)
* or the creator may spend more time in wait_task_inactive().
*/
preempt_disable();
+ if (test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
+ preempt_enable();
+ create->result = ERR_PTR(-EINTR);
+ complete(done);
+ do_exit(0);
+ }
complete(done);
schedule_preempt_disabled();
preempt_enable();

- ret = -EINTR;
- if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
- cgroup_kthread_ready();
- __kthread_parkme(self);
- ret = threadfn(data);
- }
- kthread_exit(ret);
+ cgroup_kthread_ready();
+ __kthread_parkme(self);
+ /* Run the actual thread function. */
+ kthread_exit(threadfn(data));
}

/* called from kernel_clone() to get node information for about to be created task */

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+3538a6...@syzkaller.appspotmail.com

Tested on:

commit: a2220b54 Merge branch 'cn10kb-mac-block-support'

git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master

console output: https://syzkaller.appspot.com/x/log.txt?x=1589fa4d880000

kernel config: https://syzkaller.appspot.com/x/.config?x=c608c21151db14f2
dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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=1473515b880000

[Hillf Danton]

On 07 Dec 2022 17:43:04 +0000 David Howells <dhow...@redhat.com>
>
> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next=

> .git master
>
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index f97fd01a2932..1335c89c6225 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -336,7 +336,6 @@ static int kthread(void *_create)

> void *data =3D create->data;

> struct completion *done;
> struct kthread *self;
> - int ret;

> =
>
> self =3D to_kthread(current);
> =

>
> @@ -365,17 +364,20 @@ static int kthread(void *_create)
> * or the creator may spend more time in wait_task_inactive().
> */
> preempt_disable();
> + if (test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
> + preempt_enable();

> + create->result =3D ERR_PTR(-EINTR);

> + complete(done);
> + do_exit(0);
> + }

Where is KTHREAD_SHOULD_STOP coming from? Given
1)
io_thread = kthread_run(rxrpc_io_thread, local,
"krxrpcio/%u", ntohs(udp_conf.local_udp_port));
if (IS_ERR(io_thread)) {
ret = PTR_ERR(io_thread);
goto error_sock;
}

local->io_thread = io_thread;
2)
kthread_stop(local->io_thread);

nobody knows the kthread before updating local->io_thread.

> complete(done);
> schedule_preempt_disabled();
> preempt_enable();
> =
>
> - ret =3D -EINTR;

> - if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
> - cgroup_kthread_ready();
> - __kthread_parkme(self);

> - ret =3D threadfn(data);

> - }
> - kthread_exit(ret);
> + cgroup_kthread_ready();
> + __kthread_parkme(self);
> + /* Run the actual thread function. */
> + kthread_exit(threadfn(data));
> }

> =
>
> /* called from kernel_clone() to get node information for about to be cre=

> ated task */
> diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
> index 44222923c0d1..24ee585d9aaf 100644
> --- a/net/rxrpc/local_object.c
> +++ b/net/rxrpc/local_object.c

> @@ -357,10 +357,11 @@ struct rxrpc_local *rxrpc_use_local(struct rxrpc_loc=
> al *local,
> */
> void rxrpc_unuse_local(struct rxrpc_local *local, enum rxrpc_local_trace =
> why)
> {
> - unsigned int debug_id =3D local->debug_id;

> + unsigned int debug_id;
> int r, u;

> =
>
> if (local) {
> + debug_id =3D local->debug_id;
> r =3D refcount_read(&local->ref);
> u =3D atomic_dec_return(&local->active_users);
> trace_rxrpc_local(debug_id, why, r, u);
>
>

[David Howells]

Hillf Danton <hda...@sina.com> wrote:

> Where is KTHREAD_SHOULD_STOP coming from? Given

Fair point.

David

[David Howells]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index e7dccab7b741..37f3aec784cc 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -287,6 +287,7 @@ struct rxrpc_local {
struct hlist_node link;
struct socket *socket; /* my UDP socket */
struct task_struct *io_thread;
+ struct completion io_thread_ready; /* Indication that the I/O thread started */
struct rxrpc_sock __rcu *service; /* Service(s) listening on this endpoint */
struct rw_semaphore defrag_sem; /* control re-enablement of IP DF bit */
struct sk_buff_head rx_queue; /* Received packets */
diff --git a/net/rxrpc/io_thread.c b/net/rxrpc/io_thread.c
index d83ae3193032..e460e4151c16 100644
--- a/net/rxrpc/io_thread.c
+++ b/net/rxrpc/io_thread.c
@@ -426,6 +426,8 @@ int rxrpc_io_thread(void *data)
struct rxrpc_call *call;
struct sk_buff *skb;

+ complete(&local->io_thread_ready);
+
skb_queue_head_init(&rx_queue);

set_user_nice(current, MIN_NICE);
diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 44222923c0d1..d8dfd5459f50 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -96,6 +96,7 @@ static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
atomic_set(&local->active_users, 1);
local->rxnet = rxnet;
INIT_HLIST_NODE(&local->link);
+ init_completion(&local->io_thread_ready);
init_rwsem(&local->defrag_sem);
skb_queue_head_init(&local->rx_queue);
INIT_LIST_HEAD(&local->call_attend_q);
@@ -189,6 +190,7 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
goto error_sock;
}

+ wait_for_completion(&local->io_thread_ready);
local->io_thread = io_thread;
_leave(" = 0");
return 0;
@@ -357,10 +359,11 @@ struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local,
*/
void rxrpc_unuse_local(struct rxrpc_local *local, enum rxrpc_local_trace why)
{
- unsigned int debug_id = local->debug_id;

+ unsigned int debug_id;
int r, u;

if (local) {
+ debug_id = local->debug_id;
r = refcount_read(&local->ref);

u = atomic_dec_return(&local->active_users);
trace_rxrpc_local(debug_id, why, r, u);

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+3538a6...@syzkaller.appspotmail.com

Tested on:

commit: d8b879c0 Merge branch 'net-ethernet-ti-am65-cpsw-fix-s..

git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master

console output: https://syzkaller.appspot.com/x/log.txt?x=14186857880000

kernel config: https://syzkaller.appspot.com/x/.config?x=c608c21151db14f2
dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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=1257cd23880000

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+3538a6...@syzkaller.appspotmail.com

Tested on:

commit: efb7555b rxrpc: Fix I/O thread stop
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/ afs-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=10a1192f880000
kernel config: https://syzkaller.appspot.com/x/.config?x=331c73ac8d6e1cab

dashboard link: https://syzkaller.appspot.com/bug?extid=3538a6a72efa8b059c38
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.