f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()

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Summary

CVECVE-2026-31715
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-01 14:16:21 UTC
Updated2026-06-19 13:16:27 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io() The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000170000 probability, percentile 0.040610000 (date 2026-05-05)

Problem Types: CWE-416

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 7dbdab4430e4654db9aacef12b9b3b8b29ca25cb git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e ffb94770dbdfb5411be5d9f44a960b010ec890ad git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 0d40b26377f891e6dcb6efaf8ef9374c99be1b1d git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 1171f329cf1c175321251ac40fd126150d7ad1e8 git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 7be222de96c0f9eee6e65eeb017ef855ee185cfa git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 963d2e24d9d92a31e6773b0f642214f10013ebf7 git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 188bb65f247a7a7c62f287c9a263aee3cad96fa5 git Not specified
CNA Linux Linux affected 50fa53eccf9f911a5b435248a2b0bd484fd82e5e 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 git Not specified
CNA Linux Linux affected 4.19 Not specified
CNA Linux Linux unaffected 4.19 semver Not specified
CNA Linux Linux unaffected 5.10.259 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.210 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.176 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.140 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.86 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.25 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.2 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/963d2e24d9d92a31e6773b0f642214f10013ebf7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ffb94770dbdfb5411be5d9f44a960b010ec890ad 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0d40b26377f891e6dcb6efaf8ef9374c99be1b1d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/7dbdab4430e4654db9aacef12b9b3b8b29ca25cb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/188bb65f247a7a7c62f287c9a263aee3cad96fa5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1171f329cf1c175321251ac40fd126150d7ad1e8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7be222de96c0f9eee6e65eeb017ef855ee185cfa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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