Bug 2425075 (CVE-2023-54076)

Summary: CVE-2023-54076 kernel: smb: client: fix missed ses refcounting
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A use-after-free vulnerability was found in the Linux kernel's SMB client implementation. When handling SMB sessions with DFS (Distributed File System) root sessions, the code fails to properly increment the reference count for both the session and its dfs_root_ses. This can cause the dfs_root_ses to be freed prematurely in a subsequent cifs_put_smb_ses() call, leading to a use-after-free condition.
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Description OSIDB Bzimport 2025-12-24 13:06:43 UTC 
In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix missed ses refcounting

Use new cifs_smb_ses_inc_refcount() helper to get an active reference
of @ses and @ses->dfs_root_ses (if set).  This will prevent
@ses->dfs_root_ses of being put in the next call to cifs_put_smb_ses()
and thus potentially causing an use-after-free bug.
Comment 1 Alexander B 2025-12-25 04:24:07 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122433-CVE-2023-54076-e317@gregkh/T