Re: [syzbot] BUG: unable to handle kernel NULL pointer dereference in shmem_evict_inode

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: corrupted list in __sk_destruct

list_del corruption. next->prev should be ffff0000d3a73b80, but was 0000000000000000. (next=ffff0000d43c9680)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:64!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 3500 Comm: syz-executor.1 Not tainted 6.1.0-rc4-syzkaller-00039-g1621b6eaebf7-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __list_del_entry_valid+0xcc/0xd0 lib/list_debug.c:62
lr : __list_del_entry_valid+0xcc/0xd0 lib/list_debug.c:62
sp : ffff800012d8bb50
x29: ffff800012d8bb50 x28: 00000000002e0003 x27: 0000000000000000
x26: ffff0000cdf283a8 x25: 0000000000000000 x24: 0000000000000001
x23: 0000000000000000 x22: ffff0000cc951cf0 x21: ffff0000d3a73b80
x20: 0000000000000000 x19: ffff0000cc951c90 x18: 00000000000000c0
x17: 20747562202c3038 x16: ffff80000db2a158 x15: ffff0000c7b39a40
x14: 0000000000000000 x13: 00000000ffffffff x12: ffff0000c7b39a40
x11: ff808000081c06c8 x10: 0000000000000000 x9 : 09ff774b4a8bd800
x8 : 09ff774b4a8bd800 x7 : ffff80000c01881c x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0001fefddcc8 x1 : 0000000100000001 x0 : 000000000000006d
Call trace:
 __list_del_entry_valid+0xcc/0xd0 lib/list_debug.c:62
 __list_del_entry include/linux/list.h:134 [inline]
 list_del include/linux/list.h:148 [inline]
 ref_tracker_free+0x188/0x340 lib/ref_tracker.c:146
 netns_tracker_free include/net/net_namespace.h:335 [inline]
 put_net_track include/net/net_namespace.h:349 [inline]
 __sk_destruct+0x27c/0x4e4 net/core/sock.c:2151
 sk_destruct net/core/sock.c:2167 [inline]
 __sk_free+0x238/0x290 net/core/sock.c:2178
 sk_free+0x54/0xbc net/core/sock.c:2189
 sock_put include/net/sock.h:1987 [inline]
 tcp_close+0x78/0xe0 net/ipv4/tcp.c:3034
 inet_release+0xc8/0xe4 net/ipv4/af_inet.c:428
 __sock_release net/socket.c:650 [inline]
 sock_close+0x50/0xf0 net/socket.c:1365
 __fput+0x198/0x3e4 fs/file_table.c:320
 ____fput+0x20/0x30 fs/file_table.c:348
 task_work_run+0x100/0x148 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Code: d4210000 d001b140 913ac800 94a82811 (d4210000) 
---[ end trace 0000000000000000 ]---


Tested on:

commit:         1621b6ea Merge branch 'for-next/fixes' into for-kernelci
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=165acf59880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
dashboard link: https://syzkaller.appspot.com/bug?extid=b90b43fd4c6589e96a39
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10a9080d880000