Bug 2414731 (CVE-2025-40203)

Summary: CVE-2025-40203 kernel: listmount: don't call path_put() under namespace semaphore
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel’s listmount() function: the code calls path_put() while holding the namespace semaphore. Under certain conditions, this can drop the final reference to a path object inappropriately, leading to unstable behavior in mount/namespace operations.
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Description OSIDB Bzimport 2025-11-12 23:03:18 UTC 
In the Linux kernel, the following vulnerability has been resolved:

listmount: don't call path_put() under namespace semaphore

Massage listmount() and make sure we don't call path_put() under the
namespace semaphore. If we put the last reference we're fscked.
Comment 1 Alexander B 2025-11-13 11:10:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025111247-CVE-2025-40203-c83b@gregkh/T