CVE-2025-38626

f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode

MEDIUM

5.5

CVSS Score

Published: August 22, 2025 at 04:00 PM UTC

Updated: June 17, 2026 at 09:17 AM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

MEDIUM5.5

Exploit prediction

EPSS 0.2%

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode w/ "mode=lfs" mount option, generic/299 will cause system panic as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2835! Call Trace: <TASK> f2fs_allocate_data_block+0x6f4/0xc50 f2fs_map_blocks+0x970/0x1550 f2fs_iomap_begin+0xb2/0x1e0 iomap_iter+0x1d6/0x430 __iomap_dio_rw+0x208/0x9a0 f2fs_file_write_iter+0x6b3/0xfa0 aio_write+0x15d/0x2e0 io_submit_one+0x55e/0xab0 __x64_sys_io_submit+0xa5/0x230 do_syscall_64+0x84/0x2f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0010:new_curseg+0x70f/0x720 The root cause of we run out-of-space is: in f2fs_map_blocks(), f2fs may trigger foreground gc only if it allocates any physical block, it will be a little bit later when there is multiple threads writing data w/ aio/dio/bufio method in parallel, since we always use OPU in lfs mode, so f2fs_map_blocks() does block allocations aggressively. In order to fix this issue, let's give a chance to trigger foreground gc in prior to block allocation in f2fs_map_blocks().

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

4.8 ≤ v < 5.15.2094.8 ≤ v < 6.1.1674.8 ≤ v < 6.12.424.8 ≤ v < 6.15.104.8 ≤ v < 6.16.14.8 ≤ v < 6.174.8 ≤ v < 6.6.1026.13 ≤ v < 6.15.106.16 ≤ v < 6.16.16.7 ≤ v < 6.12.4236abef4e796d382e81a0c2d21ea5327481dd71544.8

Vendor states this is fixed in 1005a3ca28e90c7a64fa43023f866b960a60f791 (fixed)

Vendor states this is fixed in 264ede8a52f18647ed5bb5f2bd9bf54f556ad8f5 (fixed)

Vendor states this is fixed in 385e64a0744584397b4b52b27c96703516f39968 (fixed)

Vendor states this is fixed in 82765ce5c7a56f9309ee45328e763610eaf11253 (fixed)

Vendor states this is fixed in c737047f4665232d1e26b3620bc62df334545451 (fixed)

Vendor states this is fixed in d2f280f43a2a9d918fd23169ff3a6f3b65c7cec5 (fixed)

Vendor states this is fixed in f289690f50a01c3e085d87853392d5b7436a4cee (fixed)

Vendor states this is fixed in 4.8 (unaffected)

Vendor states this is fixed in 5.15.209 (unaffected)

Vendor states this is fixed in 6.1.167 (unaffected)

Vendor states this is fixed in 6.12.42 (unaffected)

Vendor states this is fixed in 6.15.10 (unaffected)