CVE-2023-52779 Information

Description

In the Linux kernel the following vulnerability has been resolved:

fs: Pass AT_GETATTR_NOSEC flag to getattr interface function

When vfs_getattr_nosec() calls a filesystem’s getattr interface function then the ’nosec’ should propagate into this function so that vfs_getattr_nosec() can again be called from the filesystem’s gettattr rather than vfs_getattr(). The latter would add unnecessary security checks that the initial vfs_getattr_nosec() call wanted to avoid. Therefore introduce the getattr flag GETATTR_NOSEC and allow to pass with the new getattr_flags parameter to the getattr interface function. In overlayfs and ecryptfs use this flag to determine which one of the two functions to call.

In a recent code change introduced to IMA vfs_getattr_nosec() ended up calling vfs_getattr() in overlayfs which in turn called security_inode_getattr() on an exiting process that did not have current->fs set anymore which then caused a kernel NULL pointer dereference. With this change the call to security_inode_getattr() can be avoided thus avoiding the NULL pointer dereference.

Reference

https://git.kernel.org/stable/c/3fb0fa08641903304b9d81d52a379ff031dc41d4 https://git.kernel.org/stable/c/8a924db2d7b5eb69ba08b1a0af46e9f1359a9bdf