KASAN: use-after-free Read in __rxrpc_put_peer

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e132c8d7 Linux 4.14.149
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b8b57f600000
kernel config: https://syzkaller.appspot.com/x/.config?x=be18b5a03bbccd
dashboard link: https://syzkaller.appspot.com/bug?extid=d75ab31392f2a068a8d4
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+d75ab3...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __rxrpc_put_peer+0x1a5/0x1df
net/rxrpc/peer_object.c:389
Read of size 8 at addr ffff88809837d218 by task ksoftirqd/0/7

CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.149 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x197 lib/dump_stack.c:53
print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report mm/kasan/report.c:409 [inline]
kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
__rxrpc_put_peer+0x1a5/0x1df net/rxrpc/peer_object.c:389
rxrpc_put_peer net/rxrpc/ar-internal.h:999 [inline]
rxrpc_rcu_destroy_call+0xc5/0xf0 net/rxrpc/call_object.c:642
__rcu_reclaim kernel/rcu/rcu.h:195 [inline]
rcu_do_batch kernel/rcu/tree.c:2699 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
rcu_process_callbacks+0x7b8/0x12b0 kernel/rcu/tree.c:2946
__do_softirq+0x244/0x9a0 kernel/softirq.c:288
run_ksoftirqd kernel/softirq.c:670 [inline]
run_ksoftirqd+0x8c/0x1b0 kernel/softirq.c:662
smpboot_thread_fn+0x5f4/0x960 kernel/smpboot.c:164
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 15834:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
kmem_cache_alloc_trace+0x152/0x790 mm/slab.c:3618
kmalloc include/linux/slab.h:488 [inline]
kzalloc include/linux/slab.h:661 [inline]
rxrpc_alloc_local net/rxrpc/local_object.c:82 [inline]
rxrpc_lookup_local+0x586/0x14a0 net/rxrpc/local_object.c:252
rxrpc_sendmsg+0x3b1/0x610 net/rxrpc/af_rxrpc.c:525
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xce/0x110 net/socket.c:656
___sys_sendmsg+0x349/0x840 net/socket.c:2062
__sys_sendmmsg+0x152/0x3a0 net/socket.c:2152
SYSC_sendmmsg net/socket.c:2183 [inline]
SyS_sendmmsg+0x35/0x60 net/socket.c:2178
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 17:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xcc/0x270 mm/slab.c:3815
rxrpc_local_rcu+0x44/0x50 net/rxrpc/local_object.c:383
__rcu_reclaim kernel/rcu/rcu.h:195 [inline]
rcu_do_batch kernel/rcu/tree.c:2699 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
rcu_process_callbacks+0x7b8/0x12b0 kernel/rcu/tree.c:2946
__do_softirq+0x244/0x9a0 kernel/softirq.c:288

The buggy address belongs to the object at ffff88809837d200
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff88809837d200, ffff88809837d600)
The buggy address belongs to the page:
page:ffffea000260df00 count:1 mapcount:0 mapping:ffff88809837c000 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffff88809837c000 0000000000000000 0000000100000007
raw: ffffea00027f4320 ffffea00025ac020 ffff8880aa800ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809837d100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809837d180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88809837d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809837d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809837d300: 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.