In the Linux kernel, the following vulnerability has been resolved:
io_uring: fix fget leak when fs don't support nowait buffered read
Heming reported a BUG when using io_uring doing link-cp on ocfs2. [1]
Do the following steps can reproduce this BUG: mount -t ocfs2 /dev/vdc /mnt/ocfs2 cp testfile /mnt/ocfs2/ ./link-cp /mnt/ocfs2/testfile /mnt/ocfs2/testfile.1 umount /mnt/ocfs2
Then umount will fail, and it outputs: umount: /mnt/ocfs2: target is busy.
While tracing umount, it blames mnt_get_count() not return as expected. Do a deep investigation for fget()/fput() on related code flow, I've finally found that fget() leaks since ocfs2 doesn't support nowait buffered read.
io_issue_sqe |-io_assign_file // do fget() first |-io_read |-io_iter_do_read |-ocfs2_file_read_iter // return -EOPNOTSUPP |-kiocb_done |-io_rw_done |-__io_complete_rw_common // set REQ_F_REISSUE |-io_resubmit_prep |-io_req_prep_async // override req->file, leak happens
This was introduced by commit a196c78b5443 in v5.18. Fix it by don't re-assign req->file if it has already been assigned.
[1] https://lore.kernel.org/ocfs2-devel/[email protected]/T/#t
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade python3-perfUpgrade bpftoolUpgrade kernel-debuginfoUpgrade kernel-tools-debuginfoUpgrade kernel-headersUpgrade kernel-tools-develUpgrade python3-perf-debuginfoUpgrade kernel-libbpf-staticUpgrade kernel-develUpgrade kernelUpgrade kernel-libbpfUpgrade perf-debuginfoUpgrade kernel-libbpf-develUpgrade kernel-debuginfo-common-aarch64Upgrade perfUpgrade kernel-toolsUpgrade kernel-livepatch-6.1.19-30.43Upgrade bpftool-debuginfoUpgrade kernel-debuginfo-common-x86_64 | Oct 24, 2025 | Oct 1, 2025 |
| Debian | — | Upgrade linux | Oct 3, 2025 | Oct 3, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Oct 1, 2025 |
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