Use-after-free due to delegation race in nfsd
Summary
GSD-2021-1002600: nfsd: fix use-after-free due to delegation race. Affects Kernel versions < 148c816f10fd11df27ca6a9b3238cdd42fa72cd3. No fix is published. How to fix ↓
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Background
The nfsd package is a component of the Linux Kernel that provides support for the Network File System (NFS) protocol. NFS allows remote file systems to be mounted and accessed over a network. The nfsd module is responsible for handling NFS server requests. It manages file operations, authentication, and other NFS-related tasks.
Vulnerability Detail
The use-after-free vulnerability in nfsd is caused by a race condition during delegation handling. Delegation is a feature in NFS that allows a client to cache file metadata and perform certain operations locally without contacting the server. However, due to a race condition, a client can release a delegation while it is still being used by another thread, leading to a use-after-free scenario. An attacker could potentially exploit this vulnerability to execute arbitrary code or cause a denial-of-service condition.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
There is no known workaround for this vulnerability. It is recommended to apply the fix by updating the Linux Kernel.
Conclusion
The use-after-free vulnerability in nfsd can be mitigated by updating the Linux Kernel to version v5.15.8 or later. It is recommended to apply the fix as soon as possible to ensure the security and stability of NFS server deployments. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
nfsd is a component of the Linux Kernel that provides support for the Network File System (NFS) protocol. It allows remote file systems to be mounted and accessed over a network.
A use-after-free vulnerability occurs when a program continues to use a memory object after it has been freed. This can lead to various security issues, including crashes, data corruption, and potential execution of arbitrary code.
Delegation is a feature in NFS that allows a client to cache file metadata and perform certain operations locally without contacting the server. It improves performance by reducing network round trips.
An attacker could exploit this vulnerability by triggering the race condition during delegation handling. By releasing a delegation while it is still being used by another thread, the attacker can cause a use-after-free scenario and potentially execute arbitrary code or cause a denial-of-service condition.
Yes, this vulnerability has been fixed in the Linux Kernel version v5.15.8 by commit 148c816f10fd11df27ca6a9b3238cdd42fa72cd3.
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