syzbot


BUG: unable to handle kernel paging request in poll_freewait

Status: moderation: reported on 2025/12/29 13:36
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+ad9267e787bde6cef227@syzkaller.appspotmail.com
First crash: 33d, last: 33d

Sample crash report:
BUG: unable to handle page fault for address: ffff887ffffffff8
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5797 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:free_poll_entry fs/select.c:132 [inline]
RIP: 0010:poll_freewait+0x172/0x250 fs/select.c:149
Code: 00 00 00 48 8b 6b 08 4c 8d 6b 10 e8 98 c4 7c ff 48 83 ed 40 48 8d 7d 38 48 8d 75 10 48 89 f8 48 c1 e8 03 42 80 3c 20 00 75 65 <48> 8b 7d 38 e8 05 ec 53 ff 48 89 e8 48 c1 e8 03 42 80 3c 20 00 75
RSP: 0018:ffffc900034a7630 EFLAGS: 00010246
RAX: 1ffff10fffffffff RBX: ffff8880561bc000 RCX: ffffffff82422193
RDX: ffff8880672ba4c0 RSI: ffff887fffffffd0 RDI: ffff887ffffffff8
RBP: ffff887fffffffc0 R08: 0000000000000004 R09: 0000000000000009
R10: 0000000000000009 R11: ffff8880672baff0 R12: dffffc0000000000
R13: ffff8880561bc010 R14: 0000000000000009 R15: ffffc900034a7810
FS:  0000555563d7f500(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff887ffffffff8 CR3: 0000000033490000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: fffffffffffffffc DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_select+0xe52/0x17e0 fs/select.c:608
 core_sys_select+0x453/0xc20 fs/select.c:677
 do_pselect.constprop.0+0x19f/0x1e0 fs/select.c:759
 __do_sys_pselect6 fs/select.c:798 [inline]
 __se_sys_pselect6 fs/select.c:789 [inline]
 __x64_sys_pselect6+0x182/0x240 fs/select.c:789
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc2eb98f50c
Code: 29 44 24 30 80 3d 6b c0 22 00 00 4c 89 4c 24 40 4c 8d 4c 24 40 48 c7 44 24 48 08 00 00 00 74 2e 4c 89 ea b8 0e 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7c 48 8b 54 24 58 64 48 2b 14 25 28 00 00 00
RSP: 002b:00007ffeeca28780 EFLAGS: 00000202 ORIG_RAX: 000000000000010e
RAX: ffffffffffffffda RBX: 00007ffeeca28d00 RCX: 00007fc2eb98f50c
RDX: 0000000000000000 RSI: 00007ffeeca288b0 RDI: 0000000000000026
RBP: 00007ffeeca288b0 R08: 00007ffeeca287b0 R09: 00007ffeeca287c0
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffeeca28b50
R13: 0000000000000000 R14: 00007ffeeca28bd0 R15: 585858582e7a7973
 </TASK>
Modules linked in:
CR2: ffff887ffffffff8
---[ end trace 0000000000000000 ]---
RIP: 0010:free_poll_entry fs/select.c:132 [inline]
RIP: 0010:poll_freewait+0x172/0x250 fs/select.c:149
Code: 00 00 00 48 8b 6b 08 4c 8d 6b 10 e8 98 c4 7c ff 48 83 ed 40 48 8d 7d 38 48 8d 75 10 48 89 f8 48 c1 e8 03 42 80 3c 20 00 75 65 <48> 8b 7d 38 e8 05 ec 53 ff 48 89 e8 48 c1 e8 03 42 80 3c 20 00 75
RSP: 0018:ffffc900034a7630 EFLAGS: 00010246
RAX: 1ffff10fffffffff RBX: ffff8880561bc000 RCX: ffffffff82422193
RDX: ffff8880672ba4c0 RSI: ffff887fffffffd0 RDI: ffff887ffffffff8
RBP: ffff887fffffffc0 R08: 0000000000000004 R09: 0000000000000009
R10: 0000000000000009 R11: ffff8880672baff0 R12: dffffc0000000000
R13: ffff8880561bc010 R14: 0000000000000009 R15: ffffc900034a7810
FS:  0000555563d7f500(0000) GS:ffff8881248f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff887ffffffff8 CR3: 0000000033490000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: fffffffffffffffc DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 48 8b             	add    %cl,-0x75(%rax)
   5:	6b 08 4c             	imul   $0x4c,(%rax),%ecx
   8:	8d 6b 10             	lea    0x10(%rbx),%ebp
   b:	e8 98 c4 7c ff       	call   0xff7cc4a8
  10:	48 83 ed 40          	sub    $0x40,%rbp
  14:	48 8d 7d 38          	lea    0x38(%rbp),%rdi
  18:	48 8d 75 10          	lea    0x10(%rbp),%rsi
  1c:	48 89 f8             	mov    %rdi,%rax
  1f:	48 c1 e8 03          	shr    $0x3,%rax
  23:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
  28:	75 65                	jne    0x8f
* 2a:	48 8b 7d 38          	mov    0x38(%rbp),%rdi <-- trapping instruction
  2e:	e8 05 ec 53 ff       	call   0xff53ec38
  33:	48 89 e8             	mov    %rbp,%rax
  36:	48 c1 e8 03          	shr    $0x3,%rax
  3a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
  3f:	75                   	.byte 0x75

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/25 13:25 upstream ccd1cdca5cd4 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root BUG: unable to handle kernel paging request in poll_freewait
* Struck through repros no longer work on HEAD.