CVE-2026-31702f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()
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In the Linux kernel, the following vulnerability has been resolved: f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io() In f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring the F2FS_WB_CP_DATA counter to zero, unblocking f2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount CPU. The unmount path then proceeds to call f2fs_destroy_page_array_cache(sbi), which destroys sbi->page_array_slab via kmem_cache_destroy(), and eventually kfree(sbi). Meanwhile, the bio completion callback is still executing: when it reaches page_array_free(sbi, ...), it dereferences sbi->page_array_slab — a destroyed slab cache — to call kmem_cache_free(), causing a use-after-free. This is the same class of bug as CVE-2026-23234 (which fixed the equivalent race in f2fs_write_end_io() in data.c), but in the compressed writeback completion path that was not covered by that fix. Fix this by moving dec_page_count() to after page_array_free(), so that all sbi accesses complete before the counter decrement that can unblock unmount. For non-last folios (where atomic_dec_return on cic->pending_pages is nonzero), dec_page_count is called immediately before returning — page_array_free is not reached on this path, so there is no post-decrement sbi access. For the last folio, page_array_free runs while the F2FS_WB_CP_DATA counter is still nonzero (this folio has not yet decremented it), keeping sbi alive, and dec_page_count runs as the final operation.
- CVSS
- 7.8 HIGH (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Jun 14, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 4c8ff7095bef64fc47e996a938f7d57f9e077da3 before 57bc678f36ac03281e877c6b84877b43f964143f; from 4c8ff7095bef64fc47e996a938f7d57f9e077da3 before ef57cd3329b40c739b9a2e1a8a21ecc4171c6280; from 4c8ff7095bef64fc47e996a938f7d57f9e077da3 before f5154cf3ce1c8193f0c1891d3769f62740cfe6fe; from 4c8ff7095bef64fc47e996a938f7d57f9e077da3 before c76cf339b87975ae5b2c06d2d774d5667d25a12a; 4c8ff7095bef64fc47e996a938f7d57f9e077da3 builds before 2c97dcb6147c8f7f25c629b93be1e69617de5d4a; from 4c8ff7095bef64fc47e996a938f7d57f9e077da3 before 39d4ee19c1e7d753dd655aebee632271b171f43a | CNA record |
linux linux_kernel linux:linux_kernel | from 5.6 before 6.6.136; from 6.7 before 6.12.84; from 6.13 before 6.18.25; from 6.19 before 7.0.2; 7.1; 7.1 | NVD |
References
- https://git.kernel.org/stable/c/57bc678f36ac03281e877c6b84877b43f964143f
- https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280patch
- https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fepatch
- https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12apatch
- https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4apatch
- https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43apatch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.