syzbot


general protection fault in iomap_read_end

Status: moderation: reported on 2026/01/25 03:06
Subsystems: iomap
[Documentation on labels]
Reported-by: syzbot+fd66964b91e778f8b400@syzkaller.appspotmail.com
First crash: 4d23h, last: 4d23h

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 UID: 0 PID: 5344 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cc cc cc cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc9000ee5df50 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffffffff8b7d16ad RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8b7d16ad RDI: 0000000000000003
RBP: ffffffff825ed37e R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f9df0f R12: 0000000000000000
R13: 000000000000001a R14: 000000000000001a R15: 0000000000000001
FS:  00007fa2bdab36c0(0000) GS:ffff88808cf1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f074e5c4ad8 CR3: 0000000012634000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kasan_check_byte+0x12/0x40 mm/kasan/common.c:573
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x84/0x330 kernel/locking/lockdep.c:5842
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 iomap_read_end+0x4e/0x2d0 fs/iomap/buffered-io.c:458
 iomap_readahead+0x993/0xc10 fs/iomap/buffered-io.c:643
 fuse_readahead+0x202/0x270 fs/fuse/file.c:1084
 read_pages+0x193/0x5a0 mm/readahead.c:163
 page_cache_ra_unbounded+0x74f/0x980 mm/readahead.c:302
 do_page_cache_ra mm/readahead.c:332 [inline]
 force_page_cache_ra mm/readahead.c:361 [inline]
 page_cache_sync_ra+0x433/0xc40 mm/readahead.c:579
 filemap_get_pages+0x4c5/0x1ec0 mm/filemap.c:2690
 filemap_read+0x447/0x1230 mm/filemap.c:2800
 fuse_cache_read_iter fs/fuse/file.c:1105 [inline]
 fuse_file_read_iter+0x4a6/0x580 fs/fuse/file.c:1828
 __kernel_read+0x504/0x9b0 fs/read_write.c:530
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
 ima_calc_file_hash+0x12c3/0x17f0 security/integrity/ima/ima_crypto.c:568
 ima_collect_measurement+0x48b/0x930 security/integrity/ima/ima_api.c:293
 process_measurement+0x12e0/0x1cb0 security/integrity/ima/ima_main.c:406
 ima_file_check+0xdf/0x130 security/integrity/ima/ima_main.c:663
 security_file_post_open+0xb3/0x260 security/security.c:2652
 do_open fs/namei.c:4639 [inline]
 path_openat+0x34cb/0x3e20 fs/namei.c:4796
 do_filp_open+0x22d/0x490 fs/namei.c:4823
 do_sys_openat2+0x12f/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_open fs/open.c:1444 [inline]
 __se_sys_open fs/open.c:1440 [inline]
 __x64_sys_open+0x11e/0x150 fs/open.c:1440
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa2bcb9acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa2bdab3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fa2bce15fa0 RCX: 00007fa2bcb9acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000000c0
RBP: 00007fa2bcc08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa2bce16038 R14: 00007fa2bce15fa0 R15: 00007fff06e0b1d8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cc cc cc cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc9000ee5df50 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffffffff8b7d16ad RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8b7d16ad RDI: 0000000000000003
RBP: ffffffff825ed37e R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f9df0f R12: 0000000000000000
R13: 000000000000001a R14: 000000000000001a R15: 0000000000000001
FS:  00007fa2bdab36c0(0000) GS:ffff88808cf1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f074e5c4ad8 CR3: 0000000012634000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess), 4 bytes skipped:
   0:	0f 1f 40 00          	nopl   0x0(%rax)
   4:	90                   	nop
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	0f 1f 40 d6          	nopl   -0x2a(%rax)
  18:	48 c1 ef 03          	shr    $0x3,%rdi
  1c:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  23:	fc ff df
* 26:	0f b6 04 07          	movzbl (%rdi,%rax,1),%eax <-- trapping instruction
  2a:	3c 08                	cmp    $0x8,%al
  2c:	0f 92 c0             	setb   %al
  2f:	c3                   	ret
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	cc                   	int3
  34:	cc                   	int3
  35:	66                   	data16
  36:	66                   	data16
  37:	66                   	data16
  38:	66                   	data16
  39:	66                   	data16
  3a:	66                   	data16
  3b:	2e                   	cs

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/21 03:02 upstream c03e9c42ae8f 2494e18d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in iomap_read_end
* Struck through repros no longer work on HEAD.