block, bfq: fix possible uaf for 'bfqq->bic'
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
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix possible uaf for 'bfqq->bic' Our test report a uaf for 'bfqq->bic' in 5.10: ================================================================== BUG: KASAN: use-after-free in bfq_select_queue+0x378/0xa30 CPU: 6 PID: 2318352 Comm: fsstress Kdump: loaded Not tainted 5.10.0-60.18.0.50.h602.kasan.eulerosv2r11.x86_64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-20220320_160524-szxrtosci10000 04/01/2014 Call Trace: bfq_select_queue+0x378/0xa30 bfq_dispatch_request+0xe8/0x130 blk_mq_do_dispatch_sched+0x62/0xb0 __blk_mq_sched_dispatch_requests+0x215/0x2a0 blk_mq_sched_dispatch_requests+0x8f/0xd0 __blk_mq_run_hw_queue+0x98/0x180 __blk_mq_delay_run_hw_queue+0x22b/0x240 blk_mq_run_hw_queue+0xe3/0x190 blk_mq_sched_insert_requests+0x107/0x200 blk_mq_flush_plug_list+0x26e/0x3c0 blk_finish_plug+0x63/0x90 __iomap_dio_rw+0x7b5/0x910 iomap_dio_rw+0x36/0x80 ext4_dio_read_iter+0x146/0x190 [ext4] ext4_file_read_iter+0x1e2/0x230 [ext4] new_sync_read+0x29f/0x400 vfs_read+0x24e/0x2d0 ksys_read+0xd5/0x1b0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x61/0xc6 Commit 3bc5e683c67d ("bfq: Split shared queues on move between cgroups") changes that move process to a new cgroup will allocate a new bfqq to use, however, the old bfqq and new bfqq can point to the same bic: 1) Initial state, two process with io in the same cgroup. Process 1 Process 2 (BIC1) (BIC2) | Λ | Λ | | | | V | V | bfqq1 bfqq2 2) bfqq1 is merged to bfqq2. Process 1 Process 2 (BIC1) (BIC2) | | \-------------\| V bfqq1 bfqq2(coop) 3) Process 1 exit, then issue new io(denoce IOA) from Process 2. (BIC2) | Λ | | V | bfqq2(coop) 4) Before IOA is completed, move Process 2 to another cgroup and issue io. Process 2 (BIC2) Λ |\--------------\ | V bfqq2 bfqq3 Now that BIC2 points to bfqq3, while bfqq2 and bfqq3 both point to BIC2. If all the requests are completed, and Process 2 exit, BIC2 will be freed while there is no guarantee that bfqq2 will be freed before BIC2. Fix the problem by clearing bfqq->bic while bfqq is detached from bic.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
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 | 5.10.121 to before 5.10.175; 5.15.46 to before 5.15.86; 5.4.198 to before 5.5; 5.17.14 to before 5.18; 5.18.3 to before 5.19 | 5.10.175, 5.15.86, 5.5, 5.18, 5.19 | Patch available | CNA |
| Linux | Linux | 5.19 and later | 5.10.175, 5.15.86, 6.0.16, 6.1.2, 6.2 | Patch available | CNA |
- Linux VendorLinux Affected 5.10.121 to before 5.10.175; 5.15.46 to before 5.15.86; 5.4.198 to before 5.5; 5.17.14 to before 5.18; 5.18.3 to before 5.19 Fixed in 5.10.175, 5.15.86, 5.5, 5.18, 5.19 Patch available CNA
- Linux VendorLinux Affected 5.19 and later Fixed in 5.10.175, 5.15.86, 6.0.16, 6.1.2, 6.2 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.4.198 to before 5.5; 5.10.121 to before 5.10.175; 5.15.46 to before 5.15.86; 5.17.14 to before 5.18; 5.18.3 to before 6.0.16; 6.1 to before 6.1.2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.4.198 to before 5.5; 5.10.121 to before 5.10.175; 5.15.46 to before 5.15.86; 5.17.14 to before 5.18; 5.18.3 to before 6.0.16; 6.1 to before 6.1.2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.175, 5.15.86, 5.5, 5.18, 5.19
- Fix · CNA Linux (Linux) Fixed in 5.10.175, 5.15.86, 6.0.16, 6.1.2, 6.2
Red Hat 1 advisory
- RHSA-2023:6583 Released 2023-11-07 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- Red Hat CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-362.8.1.el9_3, libperf-5.14.0-362.8.1.el9_3
- Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-362.8.1.el9_3, kernel-64k-debug-devel-matched-5.14.0-362.8.1.el9_3, kernel-64k-devel-5.14.0-362.8.1.el9_3 +11
- Red Hat Enterprise Linux BaseOS (v. 9) bpftool-7.2.0-362.8.1.el9_3, kernel-5.14.0-362.8.1.el9_3, kernel-64k-5.14.0-362.8.1.el9_3 +29
- Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-362.8.1.el9_3, kernel-rt-core-5.14.0-362.8.1.el9_3, kernel-rt-debug-5.14.0-362.8.1.el9_3 +9
- Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-362.8.1.el9_3, kernel-rt-core-5.14.0-362.8.1.el9_3, kernel-rt-debug-5.14.0-362.8.1.el9_3 +11
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 4 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2022-50488
- 2026-10-03 Alias added: GHSA-ffg4-g8hm-36w4
- 2026-10-16 CISA SSVC decision points changed
References
Patch 5
- https://git.kernel.org/stable/c/5533742c7cb1bc9b1f0bf401cc397d44a3a9e07a
- https://git.kernel.org/stable/c/094f3d9314d67691cb21ba091c1b528f6e3c4893
- https://git.kernel.org/stable/c/b22fd72bfebda3956efc4431b60ddfc0a51e03e0
- https://git.kernel.org/stable/c/761564d93c8265f65543acf0a576b32d66bfa26a
- https://git.kernel.org/stable/c/64dc8c732f5c2b406cc752e6aaa1bd5471159cab
More Linux Kernel vulnerabilities
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- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- 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-2022-50488 · CVE Program
- CVE-2022-50488 · NVD
- FIRST EPSS
- GHSA-ffg4-g8hm-36w4 · GitHub Advisory Database · CC BY 4.0
- CVE-2022-50488 · Red Hat security data · CC BY 4.0
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