block, bfq: fix uaf for accessing waker_bfqq after splitting
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-416 and the CVSS impact.
Summary
In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix uaf for accessing waker_bfqq after splitting After commit 42c306ed7233 ("block, bfq: don't break merge chain in bfq_split_bfqq()"), if the current procress is the last holder of bfqq, the bfqq can be freed after bfq_split_bfqq(). Hence recored the bfqq and then access bfqq->waker_bfqq may trigger UAF. What's more, the waker_bfqq may in the merge chain of bfqq, hence just recored waker_bfqq is still not safe. Fix the problem by adding a helper bfq_waker_bfqq() to check if bfqq->waker_bfqq is in the merge chain, and current procress is the only holder.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.19.323 to before 4.20; 5.4.285 to before 5.5; 5.10.227 to before 5.11 | 4.20, 5.5, 5.11 | Patch available | CNA |
| Linux | Linux | — | — | Not affected | CNA |
- Linux VendorLinux Affected 4.19.323 to before 4.20; 5.4.285 to before 5.5; 5.10.227 to before 5.11 Fixed in 4.20, 5.5, 5.11 Patch available CNA
- Linux VendorLinux Affected — Fixed in — Not affected CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.10.227 to before 5.15.168; 5.16 to before 6.1.113; 6.2 to before 6.6.54; 6.7 to before 6.10.13; 6.11 to before 6.11.2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.10.227 to before 5.15.168; 5.16 to before 6.1.113; 6.2 to before 6.6.54; 6.7 to before 6.10.13; 6.11 to before 6.11.2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.20, 5.5, 5.11
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2024-49854
- 2026-10-03 Alias added: GHSA-8qj8-qf9j-579x
References
Patch 6
- https://git.kernel.org/stable/c/63a07379fdb6c72450cb05294461c6016b8b7726
- https://git.kernel.org/stable/c/de0456460f2abf921e356ed2bd8da87a376680bd
- https://git.kernel.org/stable/c/0780451f03bf518bc032a7c584de8f92e2d39d7f
- https://git.kernel.org/stable/c/0b8bda0ff17156cd3f60944527c9d8c9f99f1583
- https://git.kernel.org/stable/c/cae58d19121a70329cf971359e2518c93fec04fe
- https://git.kernel.org/stable/c/1ba0403ac6447f2d63914fb760c44a3b19c44eaf
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- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2024-49854 · CVE Program
- CVE-2024-49854 · NVD
- FIRST EPSS
- GHSA-8qj8-qf9j-579x · GitHub Advisory Database · CC BY 4.0
- CVE-2024-49854 · Red Hat security data · CC BY 4.0
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