UBUNTU-CVE-2026-43376: Use After Free
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free by using callrcu() for oplockinfo ksmbd currently frees oplockinfo immediately using kfree(), even though it is accessed under RCU read-side critical sections in places like opinfoget() and procshowfiles(). Since there is no RCU grace period delay between nullifying the pointer and freeing the memory, a reader can still access oplockinfo structure after it has been freed. This can leads to a use-after-free especially in opinfoget() where atomicincnotzero() is called on already freed memory. Fix this by switching to deferred freeing using callrcu().
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-aws-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1019.19~24.04.1 - Upgrade
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ubuntu/linux-azure-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1021.21~24.04.1 - Upgrade
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ubuntu/linux-gcp-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1020.22~24.04.1 - Upgrade
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ubuntu/linux-hwe-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-40.40~24.04.1 - Upgrade
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ubuntu/linux-nvidia-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1026.26 - Upgrade
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ubuntu/linux-oem-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1028.28 - Upgrade
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ubuntu/linux-oracle-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1018.18~24.04.1 - Upgrade
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ubuntu/linux-realtime-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1017.19~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.17.0-40.40 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.17.0-1019.19 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.17.0-1020.22 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.17.0-1018.18 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.17.0-1021.21 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.17.0-1017.19 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 6.17.0-40.40.1 - Compensating control
In ksmbd, replace immediate kfree() of oplock_info with deferred freeing via call_rcu(), ensuring the oplock_info pointer is nullified before the RCU callback frees the memory.