BUG: unable to handle kernel NULL pointer dereference in qlink

BUG: unable to handle kernel NULL pointer dereference in qlink_free (2)
Status: moderation: reported on 2020/09/03 02:48
Reported-by: syzbot+79a9766422a0ca34ca79@syzkaller.appspotmail.com
First crash: 30d, last: 11d

similar bugs (1):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
upstream	BUG: unable to handle kernel NULL pointer dereference in qlink_free			1	243d	242d	0/17	auto-closed as invalid on 2020/04/29 04:22

Sample crash report:

BUG: kernel NULL pointer dereference, address: 0000000000000080
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3910 Comm: systemd-udevd Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:qlink_free+0x16/0xb0 arch/x86/include/asm/paravirt.h:765
Code: 70 17 a5 ff 48 83 c4 08 c3 90 66 2e 0f 1f 84 00 00 00 00 00 41 57 41 56 53 48 83 3d 53 37 98 07 00 0f 84 88 00 00 00 49 89 f7 <48> 63 8e 80 00 00 00 9c 58 0f 1f 44 00 00 48 83 3d 44 37 98 07 00
RSP: 0018:ffffc900052c7a28 EFLAGS: 00010282
RAX: ffffea00001c0000 RBX: fa750d51e8000006 RCX: ffffea00001c0008
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888007000077
RBP: ffff888007000077 R08: ffffffff8134debc R09: ffffed1025fff799
R10: ffffed1025fff799 R11: 0000000000000000 R12: ffff888021fd2880
R13: 0000000000001000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fa91af428c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 00000000a704f000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 qlist_free_all mm/kasan/quarantine.c:168 [inline]
 quarantine_reduce+0x155/0x1c0 mm/kasan/quarantine.c:261
 __kasan_kmalloc+0x32/0x130 mm/kasan/common.c:442
 slab_post_alloc_hook+0x3e/0x290 mm/slab.h:518
 slab_alloc mm/slab.c:3312 [inline]
 kmem_cache_alloc+0x1c1/0x2d0 mm/slab.c:3482
 getname_flags+0xb8/0x610 fs/namei.c:138
 user_path_at_empty+0x28/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 vfs_statx+0xb9/0x380 fs/stat.c:202
 vfs_lstat include/linux/fs.h:3178 [inline]
 __do_sys_newlstat fs/stat.c:374 [inline]
 __se_sys_newlstat fs/stat.c:368 [inline]
 __x64_sys_newlstat+0x81/0xd0 fs/stat.c:368
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fa919db5335
Code: 69 db 2b 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 83 ff 01 48 89 f0 77 30 48 89 c7 48 89 d6 b8 06 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 03 f3 c3 90 48 8b 15 31 db 2b 00 f7 d8 64 89
RSP: 002b:00007ffc0cb3d0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000006
RAX: ffffffffffffffda RBX: 0000557ccb3cb120 RCX: 00007fa919db5335
RDX: 00007ffc0cb3d100 RSI: 00007ffc0cb3d100 RDI: 0000557ccb3ca120
RBP: 00007ffc0cb3d1c0 R08: 00007fa91a0741f8 R09: 0000000000001010
R10: 0000000000000020 R11: 0000000000000246 R12: 0000557ccb3ca120
R13: 0000557ccb3ca134 R14: 0000557ccb3c7dfd R15: 0000557ccb3c7e04
Modules linked in:
CR2: 0000000000000080
---[ end trace e654d21b59710996 ]---
RIP: 0010:qlink_free+0x16/0xb0 arch/x86/include/asm/paravirt.h:765
Code: 70 17 a5 ff 48 83 c4 08 c3 90 66 2e 0f 1f 84 00 00 00 00 00 41 57 41 56 53 48 83 3d 53 37 98 07 00 0f 84 88 00 00 00 49 89 f7 <48> 63 8e 80 00 00 00 9c 58 0f 1f 44 00 00 48 83 3d 44 37 98 07 00
RSP: 0018:ffffc900052c7a28 EFLAGS: 00010282
RAX: ffffea00001c0000 RBX: fa750d51e8000006 RCX: ffffea00001c0008
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888007000077
RBP: ffff888007000077 R08: ffffffff8134debc R09: ffffed1025fff799
R10: ffffed1025fff799 R11: 0000000000000000 R12: ffff888021fd2880
R13: 0000000000001000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fa91af428c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000080 CR3: 00000000a704f000 CR4: 00000000001506e0
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	Maintainers
ci-upstream-kasan-gce-smack-root	2020/09/18 04:48	upstream	10b82d51	8247808b	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/08/30 02:39	upstream	4d41ead6	d5a3ae1f	.config	log	report				davem@davemloft.net, kuba@kernel.org, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, yoshfuji@linux-ipv6.org