KASAN: null-ptr-deref Read in free_conf

Status: upstream: reported on 2026/10/26 07:19
Reported-by: syzbot+c2d8c33296cee48e923e@syzkaller.appspotmail.com
First crash: 11d, last: 2d23h
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: null-ptr-deref Read in free_conf 11 9 9h30m 10d 0/2 upstream: reported on 2026/10/26 18:19
upstream BUG: unable to handle kernel paging request in free_conf prio:high raid 11 syz, C 43 5d20h 45d 0/29 upstream: reported C repro on 2026/09/21 23:22

Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: null-ptr-deref in raid5_has_ppl drivers/md/raid5-log.h:54 [inline]
BUG: KASAN: null-ptr-deref in log_exit drivers/md/raid5-log.h:128 [inline]
BUG: KASAN: null-ptr-deref in free_conf+0x90/0x4b0 drivers/md/raid5.c:7419
Read of size 8 at addr 0000000000000028 by task syz.4.60/4630

CPU: 1 PID: 4630 Comm: syz.4.60 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x235/0x290 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 raid5_has_ppl drivers/md/raid5-log.h:54 [inline]
 log_exit drivers/md/raid5-log.h:128 [inline]
 free_conf+0x90/0x4b0 drivers/md/raid5.c:7419
 setup_conf+0x1679/0x29f0 drivers/md/raid5.c:7752
 raid5_run+0x8af/0x2960 drivers/md/raid5.c:7931
 md_run+0x10bf/0x2260 drivers/md/md.c:6028
 do_md_run+0x30/0x400 drivers/md/md.c:6160
 md_ioctl+0x249b/0x2880 drivers/md/md.c:7823
 blkdev_ioctl+0x37b/0x740 block/ioctl.c:626
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 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: 0033:0x7f36dc19fb19
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:00007f36dd068028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f36dc425fa0 RCX: 00007f36dc19fb19
RDX: 0000000000000000 RSI: 00000000400c0930 RDI: 0000000000000004
RBP: 00007f36dc237af8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f36dc426038 R14: 00007f36dc425fa0 R15: 00007fff590dae28
 </TASK>
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/03 11:34 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: null-ptr-deref Read in free_conf
2026/11/03 11:33 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: null-ptr-deref Read in free_conf
2026/10/26 07:18 linux-6.1.y 79807e970724 1d9ca40b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: null-ptr-deref Read in free_conf
2026/11/03 11:42 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in free_conf
2026/11/03 11:42 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in free_conf
2026/10/30 00:22 linux-6.1.y 79807e970724 b498adee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in free_conf
* Struck through repros no longer work on HEAD.