general protection fault in watchdog

From: syzbot
Date: Fri Dec 14 2018 - 07:51:07 EST

Hello,

syzbot found the following crash on:

HEAD commit: f5d582777bcb Merge branch 'for-linus' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16aca143400000
kernel config: https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
dashboard link: https://syzkaller.appspot.com/bug?extid=7713f3aa67be76b1552c
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1131381b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13bae593400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7713f3aa67be76b1552c@xxxxxxxxxxxxxxxxxxxxxxxxx

Node 0 DMA free:15908kB min:164kB low:204kB high:244kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 1019 Comm: khungtaskd Not tainted 4.20.0-rc6+ #150
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
RIP: 0010:watchdog+0x492/0x1060 kernel/hung_task.c:289
Code: 44 89 b5 30 fe ff ff 48 c1 e8 03 4c 01 e8 48 89 85 e8 fd ff ff e9 f8 00 00 00 e8 29 f3 ff ff 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 70 0a 00 00 4c 8b 73 10 bf 02 00 00 00 4c 89
RSP: 0018:ffff8881d7b37cc8 EFLAGS: 00010202
RAX: 01a5bfffffffff51 RBX: 0d2dfffffffffa7a RCX: ffffffff817f9259
RDX: 0000000000000000 RSI: ffffffff817f9147 RDI: 0d2dfffffffffa8a
xt_bpf: check failed: parse error
RBP: ffff8881d7b37f00 R08: ffff8881d7bae140 R09: ffffed103b5e5b5f
R10: ffffed103b5e5b5f R11: ffff8881daf2dafb R12: 00000000000003d6
R13: dffffc0000000000 R14: 1ffff1103af66fbb R15: 00000000003fffd7
FS: 0000000000000000(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f98b2d7c324 CR3: 00000001931bf000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lowmem_reserve[]: 0 2818 6321 6321
Node 0 DMA32 free:43812kB min:30052kB low:37564kB high:45076kB active_anon:6236kB inactive_anon:0kB active_file:0kB inactive_file:80kB unevictable:0kB writepending:0kB present:3129332kB managed:2888780kB mlocked:0kB kernel_stack:32kB pagetables:0kB bounce:0kB free_pcp:200kB local_pcp:200kB free_cma:0kB
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Modules linked in:
lowmem_reserve[]: 0 0 3503 3503
Node 0 Normal free:158644kB min:37364kB low:46704kB high:56044kB active_anon:4768kB inactive_anon:768kB active_file:556kB inactive_file:1936kB unevictable:0kB writepending:0kB present:4718592kB managed:3587816kB mlocked:0kB kernel_stack:5952kB pagetables:1172kB bounce:0kB free_pcp:2416kB local_pcp:604kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
Node 0 DMA: 1*4kB (U) 0*8kB 0*16kB 1*32kB (U) 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15908kB
Node 0 DMA32: 21*4kB (UM) 19*8kB (ME) 17*16kB (UM) 15*32kB (UME) 13*64kB (ME) 4*128kB (M) 3*256kB (UM) 16*512kB (UM) 12*1024kB (UME) 6*2048kB (UME) 2*4096kB (UM) = 44060kB
Node 0 Normal: 366*4kB (UME) 308*8kB (UME) 615*16kB (UME) 146*32kB (UME) 467*64kB (UME) 43*128kB (UM) 4*256kB (UM) 2*512kB (ME) 2*1024kB (ME) 0*2048kB 0*4096kB = 57928kB
Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
591 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap = 0kB
Total swap = 0kB
1965979 pages RAM
0 pages HighMem/MovableOnly
342853 pages reserved
0 pages cma reserved
Unreclaimable slab info:
Name Used Total
TIPC 1KB 7KB
SCTPv6 2KB 6KB
DCCPv6 2KB 7KB
DCCP 2KB 6KB
fib6_nodes 0KB 4KB
ip6_dst_cache 4KB 7KB
RAWv6 9KB 19KB
UDPv6 14KB 14KB
TCPv6 23KB 29KB
nf_conntrack 0KB 3KB
sd_ext_cdb 0KB 3KB
scsi_sense_cache 1056KB 1060KB
virtio_scsi_cmd 16KB 16KB
---[ end trace 92ff4e73865c48e6 ]---
sgpool-128 8KB 8KB
RIP: 0010:check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
RIP: 0010:watchdog+0x492/0x1060 kernel/hung_task.c:289
sgpool-64 4KB 6KB
sgpool-32 2KB 7KB
Code: 44 89 b5 30 fe ff ff 48 c1 e8 03 4c 01 e8 48 89 85 e8 fd ff ff e9 f8 00 00 00 e8 29 f3 ff ff 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 70 0a 00 00 4c 8b 73 10 bf 02 00 00 00 4c 89
sgpool-16 1KB 3KB
RSP: 0018:ffff8881d7b37cc8 EFLAGS: 00010202
RAX: 01a5bfffffffff51 RBX: 0d2dfffffffffa7a RCX: ffffffff817f9259
RDX: 0000000000000000 RSI: ffffffff817f9147 RDI: 0d2dfffffffffa8a
RBP: ffff8881d7b37f00 R08: ffff8881d7bae140 R09: ffffed103b5e5b5f
sgpool-8 0KB 3KB
mqueue_inode_cache 1KB 7KB
R10: ffffed103b5e5b5f R11: ffff8881daf2dafb R12: 00000000000003d6
R13: dffffc0000000000 R14: 1ffff1103af66fbb R15: 00000000003fffd7
bio_post_read_ctx 14KB 15KB
FS: 0000000000000000(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
bio-2 14KB 15KB
jfs_mp 7KB 7KB
nfs_commit_data 3KB 7KB
CR2: 00000000004376a0 CR3: 000000016845e000 CR4: 00000000001406f0
nfs_write_data 32KB 32KB
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
ext4_system_zone 0KB 3KB


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