BUG: unable to handle kernel paging request in free_conf

Status: upstream: reported C repro on 2026/09/21 23:22
Subsystems: raid
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+270624bb31d478afe62e@syzkaller.appspotmail.com
First crash: 39d, last: 3h09m
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ID Workflow Result Correct Bug Created Started Finished Revision
073080aa assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ BUG: unable to handle kernel paging request in free_conf 2026/08/16 00:30 2026/08/16 00:30 2026/08/16 00:35 746171ee
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[syzbot] [raid?] BUG: unable to handle kernel paging request in free_conf 0 (1) 2026/09/21 23:22

Sample crash report:
 </TASK>
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [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+0x81/0x5d0 drivers/md/raid5.c:7549
Read of size 8 at addr 0000000000000028 by task syz.3.20/5681

CPU: 0 UID: 0 PID: 5681 Comm: syz.3.20 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
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 instrument_atomic_read include/linux/instrumented.h:82 [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+0x81/0x5d0 drivers/md/raid5.c:7549
 setup_conf+0x1720/0x2ad0 drivers/md/raid5.c:7885
 raid5_run+0x8cc/0x2560 drivers/md/raid5.c:8129
 md_run+0xc3d/0x1cd0 drivers/md/md.c:6779
 do_md_run+0x35/0x720 drivers/md/md.c:6880
 array_state_store+0x958/0xe90 drivers/md/md.c:-1
 md_attr_store+0x3b7/0x640 drivers/md/md.c:6158
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f36cfd9e159
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:00007ffe9be823c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f36d0025fa0 RCX: 00007f36cfd9e159
RDX: 0000000000000006 RSI: 0000200000000a40 RDI: 0000000000000008
RBP: 00007ffe9be82430 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f36d0025fac R14: 00007f36d0025fa0 R15: 00007f36d0025fa0
 </TASK>
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/21 23:21 upstream f0100363d8c3 a8efa948 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: null-ptr-deref Read in free_conf
2026/08/14 00:02 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 a9ede23c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: unable to handle kernel paging request in free_conf
2026/09/21 21:38 upstream f0100363d8c3 a8efa948 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: null-ptr-deref Read in free_conf
2026/09/17 15:02 upstream 238650ef6c7c 4a607247 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: null-ptr-deref Read in free_conf
* Struck through repros no longer work on HEAD.