UBSAN: shift-out-of-bounds in null_process_zoned_cmd

Status: upstream: reported C repro on 2026/08/06 15:37
Subsystems: block
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+abd6a8dca0f2b7726060@syzkaller.appspotmail.com
Fix commit: 95491fb05105 null_blk: fix UBSAN shift-out-of-bounds when zone_size is 0 or overflows
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-arm32 ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root]
First crash: 39d, last: 11d
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
efd537cc assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ UBSAN: shift-out-of-bounds in null_process_zoned_cmd 2026/08/09 06:34 2026/08/09 06:34 2026/08/09 06:42 5d63f80b
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [block?] UBSAN: shift-out-of-bounds in null_process_zoned_cmd 1 (3) 2026/08/14 11:44
RFC PATCH] null_blk: fix UBSAN shift-out-of-bounds when zone_size is 0 or overflows 2 (2) 2026/08/08 15:56
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 UBSAN: shift-out-of-bounds in null_process_zoned_cmd -1 3 33d 39d 0/3 upstream: reported on 2026/08/04 19:02

Sample crash report:
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in drivers/block/null_blk/zoned.c:21:14
shift exponent -1 is negative
CPU: 0 UID: 0 PID: 6032 Comm: syz-executor192 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 lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x279/0x2a0 lib/ubsan.c:494
 null_zone_no drivers/block/null_blk/zoned.c:21 [inline]
 null_process_zoned_cmd.cold+0x17/0x38 drivers/block/null_blk/zoned.c:728
 null_handle_cmd drivers/block/null_blk/main.c:1455 [inline]
 null_queue_rq+0x664/0xfb0 drivers/block/null_blk/main.c:1703
 __blk_mq_issue_directly+0xe2/0x200 block/blk-mq.c:2694
 blk_mq_try_issue_directly+0x21b/0x420 block/blk-mq.c:2754
 blk_mq_submit_bio+0x21ec/0x3000 block/blk-mq.c:3208
 __submit_bio+0x90/0x3d0 block/blk-core.c:673
 __submit_bio_noacct_mq block/blk-core.c:756 [inline]
 submit_bio_noacct_nocheck+0x549/0xc00 block/blk-core.c:790
 submit_bio_noacct+0xd18/0x1ff0 block/blk-core.c:921
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 __bh_submit+0x721/0x950 fs/buffer.c:1225
 bh_submit fs/buffer.c:1239 [inline]
 block_read_full_folio+0x496/0x8c0 fs/buffer.c:2463
 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2516
 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4146
 read_mapping_folio include/linux/pagemap.h:1015 [inline]
 read_part_sector+0xd1/0x370 block/partitions/core.c:724
 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:357
 check_partition block/partitions/core.c:143 [inline]
 blk_add_partitions block/partitions/core.c:591 [inline]
 bdev_disk_changed+0x7b1/0x1260 block/partitions/core.c:695
 blkdev_get_whole+0x187/0x290 block/bdev.c:751
 bdev_open+0x2c7/0xe40 block/bdev.c:960
 bdev_file_open_by_dev block/bdev.c:1062 [inline]
 bdev_file_open_by_dev+0x179/0x210 block/bdev.c:1037
 disk_scan_partitions+0x1ef/0x320 block/genhd.c:387
 add_disk_final block/genhd.c:412 [inline]
 add_disk_fwnode+0x3f4/0x480 block/genhd.c:606
 add_disk include/linux/blkdev.h:800 [inline]
 null_add_dev+0x129d/0x1df0 drivers/block/null_blk/main.c:2052
 nullb_device_power_store+0x29d/0x350 drivers/block/null_blk/main.c:501
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc39344769e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fc3933ea128 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc3933ea6c0 RCX: 00007fc39344769e
RDX: 0000000000000002 RSI: 00007fc39348c03a RDI: 0000000000000003
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000011 R14: 00007ffcdf31cc10 R15: 00007ffcdf31ccf8
 </TASK>
---[ end trace ]---

Crashes (27):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/13 12:09 upstream 3d6d817622b0 039457bd .config console log report C ci-qemu-upstream UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/20 00:11 upstream bd5f485f3f02 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/17 12:34 upstream 8d3ae59288f1 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/11 14:32 upstream d58772d8520c 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/10 09:18 upstream b9b3e33b70b7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/05 10:08 upstream c21bb4193868 b3eac40e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/05 08:02 upstream c21bb4193868 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/19 11:31 upstream b126f6f5940f 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/10 17:52 upstream db2ddb871435 558388e4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/09 06:14 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/09 06:13 upstream 06cf61899d64 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/05 20:59 upstream c21bb4193868 1eed00d1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/19 22:45 upstream bd5f485f3f02 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/08 20:36 linux-next 6b8c8af514d7 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/05 11:09 linux-next cc2b5f627e8c b3eac40e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/04 19:49 linux-next cc2b5f627e8c d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/09/02 07:36 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/29 20:17 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/29 04:10 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1b8fa82cab7 bcbc8ceb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/22 22:21 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/21 22:43 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/16 18:01 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/13 01:46 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 21d6ac051080 7ae4acc7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/12 03:10 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f9054278acf4 f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/08 12:19 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci ba5cc80fd326 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/05 08:14 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7235a3e71949 b3eac40e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
2026/08/04 13:18 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7235a3e71949 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in null_process_zoned_cmd
* Struck through repros no longer work on HEAD.