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.
References
Configurations
Configuration 1 (hide)
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History
01 Jun 2026, 17:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
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06 May 2026, 18:44
| Type | Values Removed | Values Added |
|---|---|---|
| First Time |
Linux
Linux linux Kernel |
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| CWE | CWE-416 | |
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* |
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| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
| References | () https://git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a - Patch | |
| References | () https://git.kernel.org/stable/c/39d4ee19c1e7d753dd655aebee632271b171f43a - Patch | |
| References | () https://git.kernel.org/stable/c/c76cf339b87975ae5b2c06d2d774d5667d25a12a - Patch | |
| References | () https://git.kernel.org/stable/c/ef57cd3329b40c739b9a2e1a8a21ecc4171c6280 - Patch | |
| References | () https://git.kernel.org/stable/c/f5154cf3ce1c8193f0c1891d3769f62740cfe6fe - Patch |
01 May 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-01 14:16
Updated : 2026-06-01 17:16
NVD link : CVE-2026-31702
Mitre link : CVE-2026-31702
CVE.ORG link : CVE-2026-31702
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free