UBUNTU-CVE-2026-97558: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix cifsFileInfo reference leak in deferred close When cifsclose() defers a close, it hands the cifsFileInfo reference of the closing struct file to the queued work. Each execution of smb2deferredworkclose() drops one such reference. deferredclosescheduled can be false while the work is pending: the workqueue clears PENDING when the callback starts to run, before the callback clears the flag under deferredlock. A close in that interval requeues the running work, and the callback then clears the flag, leaving the requeued work pending with the flag down. A later cifsopen() can reuse the handle and its cifsclose() reaches the same branch: queuedelayedwork() fails because the work is still pending, but cifsclose() returns without dropping the closing file's reference. The cifsFileInfo count stays pinned and its tlink, dentry and server handle are leaked. Check the return value and hand off the reference only when work was actually queued. Otherwise, use the shared cifsFileInfoput(), like the moddelayedwork() branch above: the pending execution already owns its reference. This issue was found by an in-house static analysis tool.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
In cifs_close(), check the return value of queue_delayed_work() and hand off the cifsFileInfo reference only when work was actually queued; when work is already pending, use the shared _cifsFileInfo_put() path because the pending execution already owns the reference.