Vulnerabilities > CVE-2024-47660 - Race Condition vulnerability in Linux Kernel
Summary
In the Linux kernel, the following vulnerability has been resolved: fsnotify: clear PARENT_WATCHED flags lazily In some setups directories can have many (usually negative) dentries. Hence __fsnotify_update_child_dentry_flags() function can take a significant amount of time. Since the bulk of this function happens under inode->i_lock this causes a significant contention on the lock when we remove the watch from the directory as the __fsnotify_update_child_dentry_flags() call from fsnotify_recalc_mask() races with __fsnotify_update_child_dentry_flags() calls from __fsnotify_parent() happening on children. This can lead upto softlockup reports reported by users. Fix the problem by calling fsnotify_update_children_dentry_flags() to set PARENT_WATCHED flags only when parent starts watching children. When parent stops watching children, clear false positive PARENT_WATCHED flags lazily in __fsnotify_parent() for each accessed child.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Leveraging Race Conditions This attack targets a race condition occurring when multiple processes access and manipulate the same resource concurrently and the outcome of the execution depends on the particular order in which the access takes place. The attacker can leverage a race condition by "running the race", modifying the resource and modifying the normal execution flow. For instance a race condition can occur while accessing a file, the attacker can trick the system by replacing the original file with his version and cause the system to read the malicious file.
- Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the attacker could do something such as replace the file and cause an escalation of privilege.
References
- https://git.kernel.org/stable/c/3f3ef1d9f66b93913ce2171120d9226b55acd41d
- https://git.kernel.org/stable/c/f9a48bc3dd9099935751458a5bbbea4b7c28abc8
- https://git.kernel.org/stable/c/d8c42405fc3507cc43ba7e4986a773c3fc633f6e
- https://git.kernel.org/stable/c/fc1b1e135c3f72382f792e6c319fc088d5523ad5
- https://git.kernel.org/stable/c/7ef1d2e240c32b1f337a37232d037b07e3919e1a
- https://git.kernel.org/stable/c/172e422ffea20a89bfdc672741c1aad6fbb5044e