BUG: corrupted list in p9_fd

BUG: corrupted list in p9_fd_cancelled (2)
Status: upstream: reported syz repro on 2019/08/29 03:58
Reported-by: syzbot+1d26c4ed77bc6c5ed5e6@syzkaller.appspotmail.com
First crash: 555d, last: 502d

Cause bisection: failed (bisect log)

Fix bisection: failed (bisect log)

similar bugs (5):
Kernel	Title	Repro	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	BUG: corrupted list in p9_fd_cancelled	syz	done	2	455d	501d	1/1	fixed on 2020/01/03 09:37
android-54	BUG: corrupted list in p9_fd_cancelled			1	91d	91d	0/1	upstream: reported on 2020/11/30 22:08
linux-4.19	BUG: corrupted list in p9_fd_cancelled	syz	done	2	475d	537d	1/1	fixed on 2019/12/18 17:42
upstream	BUG: corrupted list in p9_fd_cancelled			16	858d	959d	0/21	auto-closed as invalid on 2019/04/23 06:51
linux-4.19	BUG: corrupted list in p9_fd_cancelled (2)			1	4d14h	4d13h	0/1	upstream: reported on 2021/02/25 15:45

Sample crash report:

list_del corruption, ffff88808ecdbfb0->next is LIST_POISON1 (dead000000000100)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:45!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 20174 Comm: syz-executor.1 Not tainted 5.3.0-rc5+ #125
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__list_del_entry_valid.cold+0x23/0x4f lib/list_debug.c:45
Code: e8 d5 06 1e fe 0f 0b 4c 89 f6 48 c7 c7 e0 26 c6 87 e8 c4 06 1e fe 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 20 26 c6 87 e8 b0 06 1e fe <0f> 0b 4c 89 e2 4c 89 f6 48 c7 c7 80 26 c6 87 e8 9c 06 1e fe 0f 0b
RSP: 0018:ffff8880994076d8 EFLAGS: 00010286
RAX: 000000000000004e RBX: 1ffff11013280ee9 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815c2526 RDI: ffffed1013280ecd
RBP: ffff8880994076f0 R08: 000000000000004e R09: ffffed1015d060d1
R10: ffffed1015d060d0 R11: ffff8880ae830687 R12: dead000000000122
R13: dead000000000100 R14: ffff88808ecdbfb0 R15: ffff88808ecdbfb8
FS:  00007fb2aca54700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffee6574f58 CR3: 00000000a8e6d000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_del_entry include/linux/list.h:131 [inline]
 list_del include/linux/list.h:139 [inline]
 p9_fd_cancelled+0x3c/0x1c0 net/9p/trans_fd.c:710
 p9_client_flush+0x1b7/0x1f0 net/9p/client.c:674
 p9_client_rpc+0x112f/0x12a0 net/9p/client.c:781
 p9_client_version net/9p/client.c:952 [inline]
 p9_client_create+0xb7f/0x1430 net/9p/client.c:1052
 v9fs_session_init+0x1e7/0x18c0 fs/9p/v9fs.c:406
 v9fs_mount+0x7d/0x920 fs/9p/vfs_super.c:120
 legacy_get_tree+0x108/0x220 fs/fs_context.c:661
 vfs_get_tree+0x8e/0x390 fs/super.c:1413
 do_new_mount fs/namespace.c:2791 [inline]
 do_mount+0x13b3/0x1c30 fs/namespace.c:3111
 ksys_mount+0xdb/0x150 fs/namespace.c:3320
 __do_sys_mount fs/namespace.c:3334 [inline]
 __se_sys_mount fs/namespace.c:3331 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459879
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb2aca53c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459879
RDX: 00000000200002c0 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 000000000075bfc8 R08: 0000000020000400 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb2aca546d4
R13: 00000000004c5e2f R14: 00000000004da930 R15: 00000000ffffffff
Modules linked in:
---[ end trace c76f5f29f0af3347 ]---
RIP: 0010:__list_del_entry_valid.cold+0x23/0x4f lib/list_debug.c:45
Code: e8 d5 06 1e fe 0f 0b 4c 89 f6 48 c7 c7 e0 26 c6 87 e8 c4 06 1e fe 0f 0b 4c 89 ea 4c 89 f6 48 c7 c7 20 26 c6 87 e8 b0 06 1e fe <0f> 0b 4c 89 e2 4c 89 f6 48 c7 c7 80 26 c6 87 e8 9c 06 1e fe 0f 0b
RSP: 0018:ffff8880994076d8 EFLAGS: 00010286
RAX: 000000000000004e RBX: 1ffff11013280ee9 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815c2526 RDI: ffffed1013280ecd
RBP: ffff8880994076f0 R08: 000000000000004e R09: ffffed1015d060d1
R10: ffffed1015d060d0 R11: ffff8880ae830687 R12: dead000000000122
R13: dead000000000100 R14: ffff88808ecdbfb0 R15: ffff88808ecdbfb8
FS:  00007fb2aca54700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffee6574f58 CR3: 00000000a8e6d000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-kasan-gce-root	2019/08/25 02:04	upstream	36146921	d21c5d9d	.config	log	report	syz
ci-upstream-linux-next-kasan-gce-root	2019/10/16 13:10	linux-next	0e9d28bc	d4ea592f	.config	log	report	syz