CVE-2025-38255
lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly()
In the Linux kernel, the following vulnerability has been resolved: lib/group_cpus: fix NULL pointer dereference from group_cpus_evenly() While testing null_blk with configfs, echo 0 > poll_queues will trigger following panic: BUG: kernel NULL pointer dereference, address: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 27 UID: 0 PID: 920 Comm: bash Not tainted 6.15.0-02023-gadbdb95c8696-dirty #1238 PREEMPT(undef) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:__bitmap_or+0x48/0x70 Call Trace: <TASK> __group_cpus_evenly+0x822/0x8c0 group_cpus_evenly+0x2d9/0x490 blk_mq_map_queues+0x1e/0x110 null_map_queues+0xc9/0x170 [null_blk] blk_mq_update_queue_map+0xdb/0x160 blk_mq_update_nr_hw_queues+0x22b/0x560 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_poll_queues_store+0xa4/0x130 [null_blk] configfs_write_iter+0x109/0x1d0 vfs_write+0x26e/0x6f0 ksys_write+0x79/0x180 __x64_sys_write+0x1d/0x30 x64_sys_call+0x45c4/0x45f0 do_syscall_64+0xa5/0x240 entry_SYSCALL_64_after_hwframe+0x76/0x7e Root cause is that numgrps is set to 0, and ZERO_SIZE_PTR is returned from kcalloc(), and later ZERO_SIZE_PTR will be deferenced. Fix the problem by checking numgrps first in group_cpus_evenly(), and return NULL directly if numgrps is zero. [[email protected]: also fix the non-SMP version]
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ 6a6dcae8f486c3f3298d0767d34505121c7b0b81; < 64a99eff8dcf1f951a544e6058341b2b19a8fdbd (affected, git) ≥ 6a6dcae8f486c3f3298d0767d34505121c7b0b81; < 29d39e0d5f16c060e32542b2cf351c09fd22b250 (affected, git) ≥ 6a6dcae8f486c3f3298d0767d34505121c7b0b81; < 911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65 (affected, git) ≥ 6a6dcae8f486c3f3298d0767d34505121c7b0b81; < df831e97739405ecbaddb85516bc7d4d1c933d6b (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
6.3 (affected) ≥ 0; < 6.3 (unaffected, semver) ≥ 6.6.96; ≤ 6.6.* (unaffected, semver) ≥ 6.12.36; ≤ 6.12.* (unaffected, semver) ≥ 6.15.5; ≤ 6.15.* (unaffected, semver) ≥ 6.16; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/64a99eff8dcf1f951a544e6058341b2b19a8fdbdCNA: Linux
- https://git.kernel.org/stable/c/29d39e0d5f16c060e32542b2cf351c09fd22b250CNA: Linux
- https://git.kernel.org/stable/c/911ef2e8a7de5b2bae8ff11fb0bd01f699e6db65CNA: Linux
- https://git.kernel.org/stable/c/df831e97739405ecbaddb85516bc7d4d1c933d6bCNA: Linux
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