BUG: unable to handle kernel paging request in stack_depot_save (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11500ba1e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9833e26bab355358
dashboard link: https://syzkaller.appspot.com/bug?extid=6810f647f9a85f15dd05
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
CC: [core...@netfilter.org da...@davemloft.net f...@strlen.de kad...@netfilter.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org netfilt...@vger.kernel.org pa...@netfilter.org]

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+6810f6...@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: ffff888214fdb558
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD c601067 P4D c601067 PUD c604067 PMD 1cc063 PTE 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_connect_worker
RIP: 0010:find_stack lib/stackdepot.c:184 [inline]
RIP: 0010:stack_depot_save+0x100/0x450 lib/stackdepot.c:245
Code: 84 f3 01 00 00 41 89 df 41 81 e7 ff ff 0f 00 4e 8b 34 fd 00 fd b2 8b 4d 85 f6 74 28 41 8d 75 ff eb 08 4d 8b 36 4d 85 f6 74 1a <41> 39 5e 08 75 f2 31 c0 45 3b 6e 0c 0f 84 84 01 00 00 4d 8b 36 4d
RSP: 0018:ffffc90000dd6ee0 EFLAGS: 00010086
RAX: 00000000528b0145 RBX: 00000000ea10b362 RCX: 0000000079af1f5b
RDX: 0000000000000800 RSI: 0000000000000019 RDI: 000000008bf81f98
RBP: ffffc90000dd6f28 R08: 0000000008b58c32 R09: ffffc90000dd6e60
R10: ffffc90000dd6e30 R11: ffffc90000dd6e40 R12: ffffc90000dd6f38
R13: 000000000000001a R14: ffff888214fdb550 R15: 000000000000b362
FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888214fdb558 CR3: 0000000062422000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
save_stack+0x5c/0x90 mm/kasan/common.c:74
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:337 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
__cache_free mm/slab.c:3426 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3757
nf_ct_ext_destroy+0x2ab/0x2e0 net/netfilter/nf_conntrack_extend.c:38
nf_conntrack_free+0x8f/0xe0 net/netfilter/nf_conntrack_core.c:1555
destroy_conntrack+0x1a2/0x270 net/netfilter/nf_conntrack_core.c:626
nf_conntrack_destroy+0xed/0x230 net/netfilter/core.c:600
nf_conntrack_put include/linux/netfilter/nf_conntrack_common.h:34 [inline]
nf_conntrack_put include/linux/netfilter/nf_conntrack_common.h:31 [inline]
nf_conntrack_in+0x9ac/0x1460 net/netfilter/nf_conntrack_core.c:1866
ipv4_conntrack_local+0x127/0x220 net/netfilter/nf_conntrack_proto.c:200
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:262 [inline]
__ip_local_out+0x403/0x870 net/ipv4/ip_output.c:114
ip_local_out+0x2d/0x1b0 net/ipv4/ip_output.c:123
__ip_queue_xmit+0x878/0x1c20 net/ipv4/ip_output.c:530
ip_queue_xmit+0x5a/0x70 include/net/ip.h:237
__tcp_transmit_skb+0x1aca/0x39b0 net/ipv4/tcp_output.c:1234
tcp_transmit_skb net/ipv4/tcp_output.c:1250 [inline]
tcp_connect+0x2f12/0x4600 net/ipv4/tcp_output.c:3657
tcp_v4_connect+0x158f/0x1d80 net/ipv4/tcp_ipv4.c:311
__inet_stream_connect+0x85c/0xec0 net/ipv4/af_inet.c:655
inet_stream_connect+0x58/0xa0 net/ipv4/af_inet.c:719
rds_tcp_conn_path_connect+0x620/0x880 net/rds/tcp_connect.c:172
rds_connect_worker+0x1b6/0x2d0 net/rds/threads.c:176
process_one_work+0xa05/0x17a0 kernel/workqueue.c:2264
worker_thread+0x98/0xe40 kernel/workqueue.c:2410
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
CR2: ffff888214fdb558
---[ end trace 478e8d4398fd8ec9 ]---
RIP: 0010:find_stack lib/stackdepot.c:184 [inline]
RIP: 0010:stack_depot_save+0x100/0x450 lib/stackdepot.c:245
Code: 84 f3 01 00 00 41 89 df 41 81 e7 ff ff 0f 00 4e 8b 34 fd 00 fd b2 8b 4d 85 f6 74 28 41 8d 75 ff eb 08 4d 8b 36 4d 85 f6 74 1a <41> 39 5e 08 75 f2 31 c0 45 3b 6e 0c 0f 84 84 01 00 00 4d 8b 36 4d
RSP: 0018:ffffc90000dd6ee0 EFLAGS: 00010086
RAX: 00000000528b0145 RBX: 00000000ea10b362 RCX: 0000000079af1f5b
RDX: 0000000000000800 RSI: 0000000000000019 RDI: 000000008bf81f98
RBP: ffffc90000dd6f28 R08: 0000000008b58c32 R09: ffffc90000dd6e60
R10: ffffc90000dd6e30 R11: ffffc90000dd6e40 R12: ffffc90000dd6f38
R13: 000000000000001a R14: ffff888214fdb550 R15: 000000000000b362
FS: 0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888214fdb558 CR3: 0000000062422000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

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