BUG: unable to handle kernel NULL pointer dereference in qlist_free_all (7)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: fb279f4e Merge branch 'i2c/for-current-fixed' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=122ae1fde00000
kernel config: https://syzkaller.appspot.com/x/.config?x=751a68849f797e8b
dashboard link: https://syzkaller.appspot.com/bug?extid=3f2f8bcb2afc42ae7292
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [and...@fb.com a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net da...@davemloft.net edum...@google.com ka...@fb.com ku...@kernel.org kuz...@ms2.inr.ac.ru linux-...@vger.kernel.org net...@vger.kernel.org songliu...@fb.com y...@fb.com yosh...@linux-ipv6.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+3f2f8b...@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000134
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 89ae6067 P4D 89ae6067 PUD a3497067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9387 Comm: syz-fuzzer Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:qlink_to_object mm/kasan/quarantine.c:137 [inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:142 [inline]
RIP: 0010:qlist_free_all+0x28/0x140 mm/kasan/quarantine.c:167
Code: d6 90 41 57 41 56 41 55 41 54 55 53 48 8b 1f 48 85 db 0f 84 08 01 00 00 48 89 f5 49 89 fd 48 85 ed 49 89 ee 0f 84 8b 00 00 00 <49> 63 86 34 01 00 00 4c 8b 23 48 29 c3 48 83 3d d3 df c4 07 00 0f
RSP: 0018:ffffc900020e7728 EFLAGS: 00010246
RAX: ffffea0000000000 RBX: ffff888000000000 RCX: ffffea0000000007
RDX: 0000000000000000 RSI: ffffffff8133356a RDI: 0000000000000007
RBP: 0000000000000000 R08: ffff8880941dc2c0 R09: fffffbfff180eb8a
R10: fffffbfff180eb89 R11: ffffffff8c075c4f R12: ffff888000000000
R13: ffffc900020e7760 R14: 0000000000000000 R15: 0000000000000286
FS: 000000c00007ce90(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000134 CR3: 0000000090aaa000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
quarantine_reduce+0x159/0x190 mm/kasan/quarantine.c:260
__kasan_kmalloc.constprop.0+0x97/0xd0 mm/kasan/common.c:496
slab_post_alloc_hook mm/slab.h:584 [inline]
slab_alloc_node mm/slab.c:3263 [inline]
kmem_cache_alloc_node_trace+0x14b/0x790 mm/slab.c:3593
__do_kmalloc_node mm/slab.c:3615 [inline]
__kmalloc_node_track_caller+0x38/0x60 mm/slab.c:3630
__kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:142
__alloc_skb+0xef/0x5a0 net/core/skbuff.c:210
alloc_skb_fclone include/linux/skbuff.h:1131 [inline]
sk_stream_alloc_skb net/ipv4/tcp.c:876 [inline]
sk_stream_alloc_skb+0x106/0xc70 net/ipv4/tcp.c:853
tcp_sendmsg_locked+0xcb0/0x3210 net/ipv4/tcp.c:1283
tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1433
inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
sock_write_iter+0x283/0x3c0 net/socket.c:1004
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write+0x49c/0x700 fs/read_write.c:483
__vfs_write+0xc9/0x100 fs/read_write.c:496
vfs_write+0x262/0x5c0 fs/read_write.c:558
ksys_write+0x1e8/0x250 fs/read_write.c:611
do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4afb40
Code: 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 49 c7 c2 00 00 00 00 49 c7 c0 00 00 00 00 49 c7 c1 00 00 00 00 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30
RSP: 002b:000000c00047b450 EFLAGS: 00000206 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000c00002e500 RCX: 00000000004afb40
RDX: 00000000000000f0 RSI: 000000c00000a3e0 RDI: 0000000000000003
RBP: 000000c00047b4a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 000000000000011e
R13: 000000c00040a000 R14: 000000000000007f R15: ffffffffffffb9bc
Modules linked in:
CR2: 0000000000000134
---[ end trace 6c0c3f7a2e50cbd3 ]---
RIP: 0010:qlink_to_object mm/kasan/quarantine.c:137 [inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:142 [inline]
RIP: 0010:qlist_free_all+0x28/0x140 mm/kasan/quarantine.c:167
Code: d6 90 41 57 41 56 41 55 41 54 55 53 48 8b 1f 48 85 db 0f 84 08 01 00 00 48 89 f5 49 89 fd 48 85 ed 49 89 ee 0f 84 8b 00 00 00 <49> 63 86 34 01 00 00 4c 8b 23 48 29 c3 48 83 3d d3 df c4 07 00 0f
RSP: 0018:ffffc900020e7728 EFLAGS: 00010246
RAX: ffffea0000000000 RBX: ffff888000000000 RCX: ffffea0000000007
RDX: 0000000000000000 RSI: ffffffff8133356a RDI: 0000000000000007
RBP: 0000000000000000 R08: ffff8880941dc2c0 R09: fffffbfff180eb8a
R10: fffffbfff180eb89 R11: ffffffff8c075c4f R12: ffff888000000000
R13: ffffc900020e7760 R14: 0000000000000000 R15: 0000000000000286
FS: 000000c00007ce90(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f09e2abd000 CR3: 0000000090aaa000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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