CVE-2023-52779

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> fs: Pass AT_GETATTR_NOSEC flag to getattr interface function<br /> <br /> When vfs_getattr_nosec() calls a filesystem&amp;#39;s getattr interface function<br /> then the &amp;#39;nosec&amp;#39; should propagate into this function so that<br /> vfs_getattr_nosec() can again be called from the filesystem&amp;#39;s gettattr<br /> rather than vfs_getattr(). The latter would add unnecessary security<br /> checks that the initial vfs_getattr_nosec() call wanted to avoid.<br /> Therefore, introduce the getattr flag GETATTR_NOSEC and allow to pass<br /> with the new getattr_flags parameter to the getattr interface function.<br /> In overlayfs and ecryptfs use this flag to determine which one of the<br /> two functions to call.<br /> <br /> In a recent code change introduced to IMA vfs_getattr_nosec() ended up<br /> calling vfs_getattr() in overlayfs, which in turn called<br /> security_inode_getattr() on an exiting process that did not have<br /> current-&gt;fs set anymore, which then caused a kernel NULL pointer<br /> dereference. With this change the call to security_inode_getattr() can<br /> be avoided, thus avoiding the NULL pointer dereference.