[syzbot] [net?] KASAN: slab-use-after-free Write in l2tp_session_delete

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 185d72112b95 net: xilinx: axienet: Enable multicast by def..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=129911fa980000
kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12521b9c980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1062bd46980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e84f50e44254/disk-185d7211.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/df64b575cc01/vmlinux-185d7211.xz
kernel image: https://storage.googleapis.com/syzbot-assets/16ad5d1d433b/bzImage-185d7211.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c041b4...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
BUG: KASAN: slab-use-after-free in l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639
Write of size 8 at addr ffff88802aaf5808 by task kworker/u8:11/2523

CPU: 0 PID: 2523 Comm: kworker/u8:11 Not tainted 6.10.0-rc4-syzkaller-00869-g185d72112b95 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1302 [inline]
l2tp_tunnel_del_work+0x1cb/0x330 net/l2tp/l2tp_core.c:1334
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 5107:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:4122 [inline]
__kmalloc_noprof+0x1f9/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]
l2tp_session_create+0x3b/0xc20 net/l2tp/l2tp_core.c:1675
pppol2tp_connect+0xca3/0x17a0 net/l2tp/l2tp_ppp.c:782
__sys_connect_file net/socket.c:2049 [inline]
__sys_connect+0x2df/0x310 net/socket.c:2066
__do_sys_connect net/socket.c:2076 [inline]
__se_sys_connect net/socket.c:2073 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2073
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 16:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2196 [inline]
slab_free mm/slub.c:4437 [inline]
kfree+0x149/0x360 mm/slub.c:4558
__sk_destruct+0x58/0x5f0 net/core/sock.c:2191
rcu_do_batch kernel/rcu/tree.c:2535 [inline]
rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2809
handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
run_ksoftirqd+0xca/0x130 kernel/softirq.c:928
smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
__call_rcu_common kernel/rcu/tree.c:3072 [inline]
call_rcu+0x167/0xa70 kernel/rcu/tree.c:3176
pppol2tp_release+0x24b/0x350 net/l2tp/l2tp_ppp.c:457
__sock_release net/socket.c:659 [inline]
sock_close+0xbc/0x240 net/socket.c:1421
__fput+0x406/0x8b0 fs/file_table.c:422
task_work_run+0x24f/0x310 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xa27/0x27e0 kernel/exit.c:874
do_group_exit+0x207/0x2c0 kernel/exit.c:1023
get_signal+0x16a1/0x1740 kernel/signal.c:2909
arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802aaf5800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 8 bytes inside of
freed 1024-byte region [ffff88802aaf5800, ffff88802aaf5c00)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2aaf0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffefff(slab)
raw: 00fff00000000040 ffff888015041dc0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000
head: 00fff00000000040 ffff888015041dc0 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000
head: 00fff00000000003 ffffea0000aabc01 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 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 1, tgid 1 (swapper/0), ts 11074988535, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
prep_new_page mm/page_alloc.c:1476 [inline]
get_page_from_freelist+0x2e43/0x2f00 mm/page_alloc.c:3420
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4678
__alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
alloc_slab_page+0x5f/0x120 mm/slub.c:2265
allocate_slab+0x5a/0x2f0 mm/slub.c:2428
new_slab mm/slub.c:2481 [inline]
___slab_alloc+0xcd1/0x14b0 mm/slub.c:3667
__slab_alloc+0x58/0xa0 mm/slub.c:3757
__slab_alloc_node mm/slub.c:3810 [inline]
slab_alloc_node mm/slub.c:3989 [inline]
__do_kmalloc_node mm/slub.c:4121 [inline]
__kmalloc_noprof+0x257/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]
alloc_workqueue+0x1b0/0x2060 kernel/workqueue.c:5667
tipc_topsrv_work_start net/tipc/topsrv.c:635 [inline]
tipc_topsrv_start net/tipc/topsrv.c:679 [inline]
tipc_topsrv_init_net+0x303/0x9d0 net/tipc/topsrv.c:725
ops_init+0x359/0x610 net/core/net_namespace.c:139
__register_pernet_operations net/core/net_namespace.c:1252 [inline]
register_pernet_operations+0x2cb/0x660 net/core/net_namespace.c:1325
register_pernet_device+0x33/0x80 net/core/net_namespace.c:1412
tipc_init+0x8d/0x190 net/tipc/core.c:168
do_one_initcall+0x248/0x880 init/main.c:1267
do_initcall_level+0x157/0x210 init/main.c:1329
page_owner free stack trace missing

Memory state around the buggy address:
ffff88802aaf5700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802aaf5780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802aaf5800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802aaf5880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802aaf5900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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#syz undup

[James Chapman]

On 25/06/2024 14:25, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 185d72112b95 net: xilinx: axienet: Enable multicast by def..
> git tree: net-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=129911fa980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
> dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12521b9c980000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1062bd46980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/e84f50e44254/disk-185d7211.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/df64b575cc01/vmlinux-185d7211.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/16ad5d1d433b/bzImage-185d7211.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c041b4...@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
> BUG: KASAN: slab-use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
> BUG: KASAN: slab-use-after-free in l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639
> Write of size 8 at addr ffff88802aaf5808 by task kworker/u8:11/2523

I'll look at this.

[Hillf Danton]

On 25/06/2024 14:25, syzbot wrote:

> syzbot found the following issue on:
>
> HEAD commit: 185d72112b95 net: xilinx: axienet: Enable multicast by def..
> git tree: net-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1062bd46980000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git 185d72112b95

--- x/net/l2tp/l2tp_core.c
+++ y/net/l2tp/l2tp_core.c
@@ -1298,8 +1298,10 @@ static void l2tp_tunnel_closeall(struct
list_for_each_safe(pos, tmp, &tunnel->session_list) {
session = list_entry(pos, struct l2tp_session, list);
list_del_init(&session->list);
+ l2tp_session_inc_refcount(session);
spin_unlock_bh(&tunnel->list_lock);
l2tp_session_delete(session);
+ l2tp_session_dec_refcount(session);
spin_lock_bh(&tunnel->list_lock);
}
spin_unlock_bh(&tunnel->list_lock);
--- x/net/l2tp/l2tp_ppp.c
+++ y/net/l2tp/l2tp_ppp.c
@@ -393,14 +393,6 @@ abort:
* Session (and tunnel control) socket create/destroy.
*****************************************************************************/

-static void pppol2tp_put_sk(struct rcu_head *head)
-{
- struct pppol2tp_session *ps;
-
- ps = container_of(head, typeof(*ps), rcu);
- sock_put(ps->__sk);
-}
-
/* Really kill the session socket. (Called from sock_put() if
* refcnt == 0.)
*/
@@ -444,22 +436,8 @@ static int pppol2tp_release(struct socke

session = pppol2tp_sock_to_session(sk);
if (session) {
- struct pppol2tp_session *ps;
-
l2tp_session_delete(session);
-
- ps = l2tp_session_priv(session);
- mutex_lock(&ps->sk_lock);
- ps->__sk = rcu_dereference_protected(ps->sk,
- lockdep_is_held(&ps->sk_lock));
- RCU_INIT_POINTER(ps->sk, NULL);
- mutex_unlock(&ps->sk_lock);
- call_rcu(&ps->rcu, pppol2tp_put_sk);
-
- /* Rely on the sock_put() call at the end of the function for
- * dropping the reference held by pppol2tp_sock_to_session().
- * The last reference will be dropped by pppol2tp_put_sk().
- */
+ l2tp_session_dec_refcount(session);
}

release_sock(sk);
@@ -469,6 +447,7 @@ static int pppol2tp_release(struct socke
* zero.
*/
sock_put(sk);
+ sock_put(sk);

return 0;

@@ -831,6 +810,7 @@ static int pppol2tp_connect(struct socke
out_no_ppp:
/* This is how we get the session context from the socket. */
sk->sk_user_data = session;
+ l2tp_session_inc_refcount(session);
rcu_assign_pointer(ps->sk, sk);
mutex_unlock(&ps->sk_lock);

--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in l2tp_tunnel_del_work

wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
==================================================================
BUG: KASAN: slab-use-after-free in l2tp_tunnel_del_work+0xea/0x3a0 net/l2tp/l2tp_core.c:1336
Read of size 8 at addr ffff8880684730b8 by task kworker/u8:0/11

CPU: 0 PID: 11 Comm: kworker/u8:0 Not tainted 6.10.0-rc4-syzkaller-00869-g185d72112b95-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601

l2tp_tunnel_del_work+0xea/0x3a0 net/l2tp/l2tp_core.c:1336

process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 6207:

kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:4122 [inline]
__kmalloc_noprof+0x1f9/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]

l2tp_session_create+0x3b/0xc20 net/l2tp/l2tp_core.c:1677
pppol2tp_connect+0xca3/0x17a0 net/l2tp/l2tp_ppp.c:761

__sys_connect_file net/socket.c:2049 [inline]
__sys_connect+0x2df/0x310 net/socket.c:2066
__do_sys_connect net/socket.c:2076 [inline]
__se_sys_connect net/socket.c:2073 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2073
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 11:

kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2196 [inline]
slab_free mm/slub.c:4437 [inline]
kfree+0x149/0x360 mm/slub.c:4558

l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1304 [inline]
l2tp_tunnel_del_work+0x21d/0x3a0 net/l2tp/l2tp_core.c:1336

process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff888068473000

which belongs to the cache kmalloc-1k of size 1024

The buggy address is located 184 bytes inside of
freed 1024-byte region [ffff888068473000, ffff888068473400)

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x68470

head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffefff(slab)

raw: 00fff00000000040 ffff888015041dc0 dead000000000122 0000000000000000

raw: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000

head: 00fff00000000040 ffff888015041dc0 dead000000000122 0000000000000000

head: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000

head: 00fff00000000003 ffffea0001a11c01 ffffffffffffffff 0000000000000000

head: 0000000000000008 0000000000000000 00000000ffffffff 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 0x152820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 11, tgid 11 (kworker/u8:0), ts 100058781643, free_ts 99100548000

set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
prep_new_page mm/page_alloc.c:1476 [inline]
get_page_from_freelist+0x2e43/0x2f00 mm/page_alloc.c:3420
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4678
__alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
alloc_slab_page+0x5f/0x120 mm/slub.c:2265
allocate_slab+0x5a/0x2f0 mm/slub.c:2428
new_slab mm/slub.c:2481 [inline]
___slab_alloc+0xcd1/0x14b0 mm/slub.c:3667
__slab_alloc+0x58/0xa0 mm/slub.c:3757
__slab_alloc_node mm/slub.c:3810 [inline]
slab_alloc_node mm/slub.c:3989 [inline]
__do_kmalloc_node mm/slub.c:4121 [inline]
__kmalloc_noprof+0x257/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]

ieee802_11_parse_elems_full+0xdb/0x2880 net/mac80211/parse.c:958
ieee802_11_parse_elems_crc net/mac80211/ieee80211_i.h:2344 [inline]
ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2351 [inline]
ieee80211_inform_bss+0x15f/0x1080 net/mac80211/scan.c:79
rdev_inform_bss net/wireless/rdev-ops.h:418 [inline]
cfg80211_inform_single_bss_data+0x1121/0x2360 net/wireless/scan.c:2293
cfg80211_inform_bss_data+0x3dd/0x5a70 net/wireless/scan.c:3117
cfg80211_inform_bss_frame_data+0x3bc/0x720 net/wireless/scan.c:3207
ieee80211_bss_info_update+0x8a7/0xbc0 net/mac80211/scan.c:226
ieee80211_scan_rx+0x526/0x9c0 net/mac80211/scan.c:340
__ieee80211_rx_handle_packet net/mac80211/rx.c:5222 [inline]
ieee80211_rx_list+0x2b02/0x3780 net/mac80211/rx.c:5459
page last free pid 4760 tgid 4760 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1088 [inline]
__free_pages_ok+0xb4e/0xcc0 mm/page_alloc.c:1208
__folio_put+0x3b9/0x620 mm/swap.c:129
folio_put include/linux/mm.h:1508 [inline]
free_large_kmalloc+0x105/0x1c0 mm/slub.c:4529
kfree+0x1c4/0x360 mm/slub.c:4552
proc_sys_call_handler+0x593/0x8b0 fs/proc/proc_sysctl.c:604
new_sync_read fs/read_write.c:395 [inline]
vfs_read+0x9c4/0xbd0 fs/read_write.c:476
ksys_read+0x1a0/0x2c0 fs/read_write.c:619

do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:

ffff888068472f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888068473000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888068473080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888068473100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888068473180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: 185d7211 net: xilinx: axienet: Enable multicast by def..
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=1360bf01980000

kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=17d4ba99980000

[Hillf Danton]

On 25/06/2024 14:25, syzbot wrote:

> syzbot found the following issue on:
>
> HEAD commit: 185d72112b95 net: xilinx: axienet: Enable multicast by def..
> git tree: net-next

@@ -831,6 +809,7 @@ static int pppol2tp_connect(struct socke

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+c041b4...@syzkaller.appspotmail.com

Tested on:

commit: 185d7211 net: xilinx: axienet: Enable multicast by def..
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=15fb2299980000

kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=13856f3e980000

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

[Edward Adam Davis]

delete tunnl session list

#syz test: linux-next f76698bd9a8c

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 3596290047b2..1fd27c902d80 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -446,6 +446,7 @@ static int pppol2tp_release(struct socket *sock)
if (session) {
struct pppol2tp_session *ps;

+ list_del_init(&session->list);
l2tp_session_delete(session);

ps = l2tp_session_priv(session);

[syzbot]

Hello,

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

kernel clean failed: failed to run ["make" "-j" "64" "ARCH=x86_64" "distclean"]: exit status 2
Makefile:83: *** Cannot find a vmlinux for VMLINUX_BTF at any of " ../../vmlinux /sys/kernel/btf/vmlinux /boot/vmlinux-5.9.0-0.bpo.5-cloud-amd64". Stop.
make[2]: *** [Makefile:192: sched_ext_clean] Error 2
make[1]: *** [/syzkaller/jobs-2/linux/kernel/Makefile:1361: sched_ext] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:240: __sub-make] Error 2



Tested on:

commit: f76698bd Add linux-next specific files for 20240621
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=175c26c1980000

[Edward Adam Davis]

delete tunnl session list

#syz test: linux-next 185d72112b95

[syzbot]

Hello,

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

KASAN: slab-use-after-free Write in l2tp_session_delete

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

BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
BUG: KASAN: slab-use-after-free in l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639

Write of size 8 at addr ffff88806ca77808 by task kworker/u8:3/51

CPU: 0 PID: 51 Comm: kworker/u8:3 Not tainted 6.10.0-rc4-syzkaller-00869-g185d72112b95-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601

kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639
l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1302 [inline]
l2tp_tunnel_del_work+0x1cb/0x330 net/l2tp/l2tp_core.c:1334

process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 6223:

kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:4122 [inline]
__kmalloc_noprof+0x1f9/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]

l2tp_session_create+0x3b/0xc20 net/l2tp/l2tp_core.c:1675
pppol2tp_connect+0xca3/0x17a0 net/l2tp/l2tp_ppp.c:783

__sys_connect_file net/socket.c:2049 [inline]
__sys_connect+0x2df/0x310 net/socket.c:2066
__do_sys_connect net/socket.c:2076 [inline]
__se_sys_connect net/socket.c:2073 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2073
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5956:

kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2196 [inline]
slab_free mm/slub.c:4437 [inline]
kfree+0x149/0x360 mm/slub.c:4558

__sk_destruct+0x58/0x5f0 net/core/sock.c:2191
rcu_do_batch kernel/rcu/tree.c:2535 [inline]
rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2809
handle_softirqs+0x2c4/0x970 kernel/softirq.c:554

__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
__call_rcu_common kernel/rcu/tree.c:3072 [inline]
call_rcu+0x167/0xa70 kernel/rcu/tree.c:3176

pppol2tp_release+0x357/0x450 net/l2tp/l2tp_ppp.c:458

__sock_release net/socket.c:659 [inline]
sock_close+0xbc/0x240 net/socket.c:1421
__fput+0x406/0x8b0 fs/file_table.c:422
task_work_run+0x24f/0x310 kernel/task_work.c:180

resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]

exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]

syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88806ca77800

which belongs to the cache kmalloc-1k of size 1024

The buggy address is located 8 bytes inside of
freed 1024-byte region [ffff88806ca77800, ffff88806ca77c00)

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6ca70

head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffefff(slab)
raw: 00fff00000000040 ffff888015041dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000
head: 00fff00000000040 ffff888015041dc0 dead000000000122 0000000000000000
head: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000

head: 00fff00000000003 ffffea0001b29c01 ffffffffffffffff 0000000000000000

head: 0000000000000008 0000000000000000 00000000ffffffff 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 0x152820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 11, tgid 11 (kworker/u8:0), ts 101409670398, free_ts 101342435367

set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
prep_new_page mm/page_alloc.c:1476 [inline]
get_page_from_freelist+0x2e43/0x2f00 mm/page_alloc.c:3420
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4678
__alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
alloc_slab_page+0x5f/0x120 mm/slub.c:2265
allocate_slab+0x5a/0x2f0 mm/slub.c:2428
new_slab mm/slub.c:2481 [inline]
___slab_alloc+0xcd1/0x14b0 mm/slub.c:3667
__slab_alloc+0x58/0xa0 mm/slub.c:3757
__slab_alloc_node mm/slub.c:3810 [inline]
slab_alloc_node mm/slub.c:3989 [inline]
__do_kmalloc_node mm/slub.c:4121 [inline]
__kmalloc_noprof+0x257/0x400 mm/slub.c:4135
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]

neigh_alloc net/core/neighbour.c:494 [inline]
___neigh_create+0x691/0x2470 net/core/neighbour.c:648
ip6_finish_output2+0x1631/0x1680 net/ipv6/ip6_output.c:128
ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
NF_HOOK include/linux/netfilter.h:314 [inline]
ndisc_send_skb+0xab2/0x1380 net/ipv6/ndisc.c:509
ndisc_send_ns+0xcc/0x160 net/ipv6/ndisc.c:667
addrconf_dad_work+0xb45/0x16f0 net/ipv6/addrconf.c:4281

process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393

page last free pid 9 tgid 9 stack trace:

reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1088 [inline]

free_unref_page+0xd22/0xea0 mm/page_alloc.c:2583
discard_slab mm/slub.c:2527 [inline]
__put_partials+0xeb/0x130 mm/slub.c:2995
put_cpu_partial+0x17c/0x250 mm/slub.c:3070
__slab_free+0x2ea/0x3d0 mm/slub.c:4307
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3941 [inline]
slab_alloc_node mm/slub.c:4001 [inline]
kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4044
__alloc_skb+0x1c3/0x440 net/core/skbuff.c:656
alloc_skb include/linux/skbuff.h:1320 [inline]
alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6509
sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815
sock_alloc_send_skb include/net/sock.h:1773 [inline]
mld_newpack+0x1c3/0xa90 net/ipv6/mcast.c:1746
add_grhead net/ipv6/mcast.c:1849 [inline]
add_grec+0x1492/0x19a0 net/ipv6/mcast.c:1987
mld_send_initial_cr+0x228/0x4b0 net/ipv6/mcast.c:2233
mld_dad_work+0x44/0x500 net/ipv6/mcast.c:2259

process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312

Memory state around the buggy address:

ffff88806ca77700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88806ca77780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806ca77800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88806ca77880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88806ca77900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: 185d7211 net: xilinx: axienet: Enable multicast by def..

git tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=135c05a9980000

kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2

compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=13129e12980000