CVE-2023-54242
NoneCVSS
—
EPSS
0.2%
Published
Dec 30, 2025
CISA due date
—
Cloudanix analysis
A flaw in the Linux kernel's disk scheduling code can cause the entire system to crash when certain I/O priority settings are used.
- Exploitation
- Local Privilege
- Attacker needs
- High Privilege
- Complexity
- Trivial
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Improper Input Validation
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Division by zero in bfqq_request_over_limit when weighted sum (wsum) reaches zero, causing kernel oops and potential panic during I/O request processing in the BFQ scheduler.
Why it matters to the business
Local denial of service leading to system crashes or instability on Linux systems using the BFQ I/O scheduler, potentially disrupting workloads that involve I/O priority adjustments or specific stress testing scenarios.
How an attack unfolds
An attacker with local access invokes tools or system calls that set I/O priorities resulting in a zero weighted sum for the BFQ queue, triggering the divide-by-zero error in the request limit calculation during block I/O submission paths.
How to fix it
Update the Linux kernel to a version containing commit 1655cfc85250a224b0d9486c8136baeea33b9b5c or later equivalent stable releases that prevent the zero wsum division.
How to confirm the fix worked
Verify kernel version includes the referenced fix commit; attempt reproduction with I/O priority tools under BFQ scheduler and confirm absence of divide error oops in logs.
Typical attack path
- Obtain local user access on a Linux system using BFQ scheduler
- Execute commands or tools that manipulate I/O priorities to produce zero wsum (e.g., via ioprio settings)
- Trigger I/O operations that invoke bfqq_request_over_limit
- Cause kernel divide error leading to oops or panic
How to detect it
Inspect kernel logs for divide error oops mentioning bfqq_request_over_limit and stress-ng or ioprio-related processes; review dmesg or syslog for RIP and call traces involving bfq_limit_depth and block I/O submission.
- divide error: 0000 [#1] SMP NOPTI
- bfqq_request_over_limit+0x207/0x400
- stress-ng-iopri
What your security team should do
- Prioritize kernel upgrades to patched versions across all affected Linux deployments
- Monitor for kernel oops reports involving bfqq_request_over_limit
- Restrict unprivileged use of I/O priority manipulation where possible until patched
The record
In the Linux kernel, the following vulnerability has been resolved: block, bfq: Fix division by zero error on zero wsum When the weighted sum is zero the calculation of limit causes a division by zero error. Fix this by continuing to the next level. This was discovered by running as root: stress-ng --ioprio 0 Fixes divison by error oops: [ 521.450556] divide error: 0000 [#1] SMP NOPTI [ 521.450766] CPU: 2 PID: 2684464 Comm: stress-ng-iopri Not tainted 6.2.1-1280.native #1 [ 521.451117] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.1-0-g3208b098f51a-prebuilt.qemu.org 04/01/2014 [ 521.451627] RIP: 0010:bfqq_request_over_limit+0x207/0x400 [ 521.451875] Code: 01 48 8d 0c c8 74 0b 48 8b 82 98 00 00 00 48 8d 0c c8 8b 85 34 ff ff ff 48 89 ca 41 0f af 41 50 48 d1 ea 48 98 48 01 d0 31 d2 <48> f7 f1 41 39 41 48 89 85 34 ff ff ff 0f 8c 7b 01 00 00 49 8b 44 [ 521.452699] RSP: 0018:ffffb1af84eb3948 EFLAGS: 00010046 [ 521.452938] RAX: 000000000000003c RBX: 0000000000000000 RCX: 0000000000000000 [ 521.453262] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffb1af84eb3978 [ 521.453584] RBP: ffffb1af84eb3a30 R08: 0000000000000001 R09: ffff8f88ab8a4ba0 [ 521.453905] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8f88ab8a4b18 [ 521.454224] R13: ffff8f8699093000 R14: 0000000000000001 R15: ffffb1af84eb3970 [ 521.454549] FS: 00005640b6b0b580(0000) GS:ffff8f88b3880000(0000) knlGS:0000000000000000 [ 521.454912] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 521.455170] CR2: 00007ffcbcae4e38 CR3: 00000002e46de001 CR4: 0000000000770ee0 [ 521.455491] PKRU: 55555554 [ 521.455619] Call Trace: [ 521.455736] <TASK> [ 521.455837] ? bfq_request_merge+0x3a/0xc0 [ 521.456027] ? elv_merge+0x115/0x140 [ 521.456191] bfq_limit_depth+0xc8/0x240 [ 521.456366] __blk_mq_alloc_requests+0x21a/0x2c0 [ 521.456577] blk_mq_submit_bio+0x23c/0x6c0 [ 521.456766] __submit_bio+0xb8/0x140 [ 521.457236] submit_bio_noacct_nocheck+0x212/0x300 [ 521.457748] submit_bio_noacct+0x1a6/0x580 [ 521.458220] submit_bio+0x43/0x80 [ 521.458660] ext4_io_submit+0x23/0x80 [ 521.459116] ext4_do_writepages+0x40a/0xd00 [ 521.459596] ext4_writepages+0x65/0x100 [ 521.460050] do_writepages+0xb7/0x1c0 [ 521.460492] __filemap_fdatawrite_range+0xa6/0x100 [ 521.460979] file_write_and_wait_range+0xbf/0x140 [ 521.461452] ext4_sync_file+0x105/0x340 [ 521.461882] __x64_sys_fsync+0x67/0x100 [ 521.462305] ? syscall_exit_to_user_mode+0x2c/0x1c0 [ 521.462768] do_syscall_64+0x3b/0xc0 [ 521.463165] entry_SYSCALL_64_after_hwframe+0x5a/0xc4 [ 521.463621] RIP: 0033:0x5640b6c56590 [ 521.464006] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d 71 70 0e 00 00 74 17 b8 4a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 0 | 6.1.30 |
| Linux | Kernel | 5.17.0 | 6.1.30 |
| SUSE:Linux Enterprise High Availability Extension 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_48 | 0 | 1-150400.9.7.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
Related vulnerabilities
- CVE-2026-23226 In the Linux kernel, the following vulnerability has been resolved: ksmbd: add chann_lock… Also affects Kernel
- CVE-2026-23225 In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Don't… Also affects Kernel
- CVE-2026-23230 In the Linux kernel, the following vulnerability has been resolved: smb: client: split… Also affects Kernel
- CVE-2026-23224 In the Linux kernel, the following vulnerability has been resolved: erofs: fix UAF issue… Also affects Kernel
- CVE-2026-23227 In the Linux kernel, the following vulnerability has been resolved: drm/exynos: vidi: use… Also affects Kernel
- CVE-2026-23223 In the Linux kernel, the following vulnerability has been resolved: xfs: fix UAF in… Also affects Kernel
- CVE-2026-23228 In the Linux kernel, the following vulnerability has been resolved: smb: server: fix leak… Also affects Kernel
- CVE-2026-23229 In the Linux kernel, the following vulnerability has been resolved: crypto: virtio - Add… Also affects Kernel