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.
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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 01 May 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-01T13:56:10.591Z
Reserved: 2026-03-09T15:48:24.133Z
Link: CVE-2026-31715
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-05-01T14:16:21.637
Modified: 2026-05-01T15:24:14.893
Link: CVE-2026-31715
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.