KASAN: null-ptr-deref Write in do_page_cache_ra

Status: upstream: reported C repro on 2026/10/13 10:22
Reported-by: syzbot+4c32a15b27797f7a4feb@syzkaller.appspotmail.com
First crash: 5d07h, last: 8m

Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:87 [inline]
BUG: KASAN: null-ptr-deref in set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
BUG: KASAN: null-ptr-deref in do_page_cache_ra+0x18f/0x230 mm/readahead.c:324
Write of size 8 at addr 0000000000000000 by task udevd/429

CPU: 1 PID: 429 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_report+0x3d/0x60 mm/kasan/report.c:423
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 instrument_atomic_write include/linux/instrumented.h:87 [inline]
 set_bit include/asm-generic/bitops/instrumented-atomic.h:28 [inline]
 do_page_cache_ra+0x18f/0x230 mm/readahead.c:324
 force_page_cache_ra mm/readahead.c:360 [inline]
 page_cache_sync_ra+0x32b/0x3d0 mm/readahead.c:751
 page_cache_sync_readahead include/linux/pagemap.h:1259 [inline]
 filemap_get_pages mm/filemap.c:2706 [inline]
 filemap_read+0x6b6/0x23c0 mm/filemap.c:2801
 blkdev_read_iter+0x439/0x580 block/fops.c:668
 call_read_iter include/linux/fs.h:2276 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x46e/0x930 fs/read_write.c:470
 ksys_read+0x14a/0x260 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:621
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6010aa7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffc39939a00 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f601127d880 RCX: 00007f6010aa7407
RDX: 0000000000000200 RSI: 00007f6011276000 RDI: 0000000000000009
RBP: 000056121332c790 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000010000 R14: 000056121333b948 R15: 00007f60113a439c
 </TASK>
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000003
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 429 Comm: udevd Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:arch_set_bit include/linux/instrumented.h:87 [inline]
RIP: 0010:set_bit include/asm-generic/bitops/instrumented-atomic.h:29 [inline]
RIP: 0010:do_page_cache_ra+0x18f/0x230 mm/readahead.c:324
Code: fd ff 48 3d 01 f0 ff ff 72 10 e8 7c 1e d2 ff 49 83 ee 01 73 78 e9 87 00 00 00 49 89 c4 48 89 c7 be 08 00 00 00 e8 d1 ba 17 00 <f0> 41 80 4c 24 03 10 4c 89 e7 48 83 c7 34 be 04 00 00 00 e8 b9 ba
RSP: 0018:ffffc90001067878 EFLAGS: 00010246
RAX: ffff888118739400 RBX: 0000000000000010 RCX: ffff888118739440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900010678c8 R08: ffffffff87b777e7 R09: 1ffffffff0f6eefc
R10: dffffc0000000000 R11: fffffbfff0f6eefd R12: 0000000000000000
R13: 000000000000002f R14: 0000000000000000 R15: ffff88810b735850
FS:  00007f601127d880(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000003 CR3: 0000000118cc6000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 force_page_cache_ra mm/readahead.c:360 [inline]
 page_cache_sync_ra+0x32b/0x3d0 mm/readahead.c:751
 page_cache_sync_readahead include/linux/pagemap.h:1259 [inline]
 filemap_get_pages mm/filemap.c:2706 [inline]
 filemap_read+0x6b6/0x23c0 mm/filemap.c:2801
 blkdev_read_iter+0x439/0x580 block/fops.c:668
 call_read_iter include/linux/fs.h:2276 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x46e/0x930 fs/read_write.c:470
 ksys_read+0x14a/0x260 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:621
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6010aa7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffc39939a00 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f601127d880 RCX: 00007f6010aa7407
RDX: 0000000000000200 RSI: 00007f6011276000 RDI: 0000000000000009
RBP: 000056121332c790 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000010000 R14: 000056121333b948 R15: 00007f60113a439c
 </TASK>
Modules linked in:
CR2: 0000000000000003
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_set_bit include/linux/instrumented.h:87 [inline]
RIP: 0010:set_bit include/asm-generic/bitops/instrumented-atomic.h:29 [inline]
RIP: 0010:do_page_cache_ra+0x18f/0x230 mm/readahead.c:324
Code: fd ff 48 3d 01 f0 ff ff 72 10 e8 7c 1e d2 ff 49 83 ee 01 73 78 e9 87 00 00 00 49 89 c4 48 89 c7 be 08 00 00 00 e8 d1 ba 17 00 <f0> 41 80 4c 24 03 10 4c 89 e7 48 83 c7 34 be 04 00 00 00 e8 b9 ba
RSP: 0018:ffffc90001067878 EFLAGS: 00010246
RAX: ffff888118739400 RBX: 0000000000000010 RCX: ffff888118739440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900010678c8 R08: ffffffff87b777e7 R09: 1ffffffff0f6eefc
R10: dffffc0000000000 R11: fffffbfff0f6eefd R12: 0000000000000000
R13: 000000000000002f R14: 0000000000000000 R15: ffff88810b735850
FS:  00007f601127d880(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000003 CR3: 0000000118cc6000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	48 3d 01 f0 ff ff    	cmp    $0xfffffffffffff001,%rax
   6:	72 10                	jb     0x18
   8:	e8 7c 1e d2 ff       	call   0xffd21e89
   d:	49 83 ee 01          	sub    $0x1,%r14
  11:	73 78                	jae    0x8b
  13:	e9 87 00 00 00       	jmp    0x9f
  18:	49 89 c4             	mov    %rax,%r12
  1b:	48 89 c7             	mov    %rax,%rdi
  1e:	be 08 00 00 00       	mov    $0x8,%esi
  23:	e8 d1 ba 17 00       	call   0x17baf9
* 28:	f0 41 80 4c 24 03 10 	lock orb $0x10,0x3(%r12) <-- trapping instruction
  2f:	4c 89 e7             	mov    %r12,%rdi
  32:	48 83 c7 34          	add    $0x34,%rdi
  36:	be 04 00 00 00       	mov    $0x4,%esi
  3b:	e8                   	.byte 0xe8
  3c:	b9                   	.byte 0xb9
  3d:	ba                   	.byte 0xba

Crashes (2228):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 22:02 android14-6.1 48e3cd973485 432c0077 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/16 18:57 android14-6.1 b44b71789840 4c840a2f .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/16 05:12 android14-6.1 b44b71789840 3f2522c6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/15 11:30 android14-6.1 06aabb3c5541 8fb0ae89 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/14 21:21 android14-6.1 06aabb3c5541 1a71827b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/14 17:12 android14-6.1 e3b8fb598ad4 1a71827b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/14 05:52 android14-6.1 e3b8fb598ad4 7321cd29 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/14 05:30 android14-6.1 e3b8fb598ad4 7321cd29 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/13 10:54 android14-6.1 31addbff5e86 5a1eeac4 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/13 10:13 android14-6.1 31addbff5e86 5a1eeac4 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 03:44 android14-6.1 48e3cd973485 432c0077 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 11:41 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 10:42 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 09:52 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 09:52 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 08:50 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 07:52 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 07:48 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 06:35 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 06:02 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 05:42 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 04:41 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 04:00 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 03:11 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 02:33 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 01:40 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/18 00:32 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 23:56 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 23:14 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 22:22 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 21:19 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 20:46 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 20:03 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 19:11 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 18:13 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 17:21 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 16:39 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 15:35 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 14:31 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 14:22 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 13:00 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 12:09 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 11:35 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 10:49 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 10:46 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 09:34 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 09:20 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 08:12 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 08:07 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 07:01 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 06:19 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 05:15 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/17 04:05 android14-6.1 48e3cd973485 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
2026/10/13 04:25 android14-6.1 31addbff5e86 745a967f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: null-ptr-deref Write in do_page_cache_ra
* Struck through repros no longer work on HEAD.