KASAN: use-after-free Read in rxrpc_put_peer

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ee809c7e Linux 4.19.72
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=116c6949600000
kernel config: https://syzkaller.appspot.com/x/.config?x=ad6c5c98f4231da9
dashboard link: https://syzkaller.appspot.com/bug?extid=07381ccfc86db0750d8a
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+07381c...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __rxrpc_put_peer net/rxrpc/peer_object.c:415
[inline]
BUG: KASAN: use-after-free in rxrpc_put_peer+0x64f/0x660
net/rxrpc/peer_object.c:439
Read of size 8 at addr ffff888095293698 by task ksoftirqd/1/18

CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.19.72 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
__rxrpc_put_peer net/rxrpc/peer_object.c:415 [inline]
rxrpc_put_peer+0x64f/0x660 net/rxrpc/peer_object.c:439
rxrpc_rcu_destroy_call+0x5e/0x140 net/rxrpc/call_object.c:657
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2584 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
rcu_process_callbacks+0xba0/0x1a30 kernel/rcu/tree.c:2881
__do_softirq+0x25c/0x921 kernel/softirq.c:292
run_ksoftirqd kernel/softirq.c:653 [inline]
run_ksoftirqd+0x8e/0x110 kernel/softirq.c:645
smpboot_thread_fn+0x6a3/0xa30 kernel/smpboot.c:164
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 10082:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc mm/kasan/kasan.c:553 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
kmem_cache_alloc_trace+0x152/0x760 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:83 [inline]
rxrpc_lookup_local+0x562/0x1b70 net/rxrpc/local_object.c:281
rxrpc_sendmsg+0x36f/0x5b0 net/rxrpc/af_rxrpc.c:573
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:632
___sys_sendmsg+0x3e2/0x920 net/socket.c:2115
__sys_sendmmsg+0x1bf/0x4e0 net/socket.c:2210
__do_sys_sendmmsg net/socket.c:2239 [inline]
__se_sys_sendmmsg net/socket.c:2236 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2236
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10095:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3503 [inline]
kfree+0xcf/0x220 mm/slab.c:3822
rxrpc_local_rcu+0x53/0x60 net/rxrpc/local_object.c:500
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2584 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
rcu_process_callbacks+0xba0/0x1a30 kernel/rcu/tree.c:2881
__do_softirq+0x25c/0x921 kernel/softirq.c:292

The buggy address belongs to the object at ffff888095293680
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff888095293680, ffff888095293a80)
The buggy address belongs to the page:
page:ffffea000254a480 count:1 mapcount:0 mapping:ffff88812c3f0ac0 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea00023bea88 ffffea00024afd08 ffff88812c3f0ac0
raw: 0000000000000000 ffff888095292000 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888095293580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888095293600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff888095293680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888095293700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888095293780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.