CVE-2026-31715
Description
In 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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | fixed | 7.0.3-1 |
| debian | sid | fixed | 7.0.3-1 |
| debian | trixie | fixed | 6.12.86-1 |
| linux-kernel | affected | 6.18.25 | |
| linux-kernel | 7.1 | affected | |
| windows | affected | |
References
- https://git.kernel.org/stable/c/1171f329cf1c175321251ac40fd126150d7ad1e8
- https://git.kernel.org/stable/c/188bb65f247a7a7c62f287c9a263aee3cad96fa5
- https://git.kernel.org/stable/c/2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53
- https://git.kernel.org/stable/c/7be222de96c0f9eee6e65eeb017ef855ee185cfa
- https://git.kernel.org/stable/c/963d2e24d9d92a31e6773b0f642214f10013ebf7
- https://www.suse.com/security/cve/CVE-2026-31715.html
- https://security-tracker.debian.org/tracker/CVE-2026-31715
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31715
CWEs
CWE-416
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.