In the Linux kernel, the following vulnerability has been resolved: Squashfs: fix uninit-value in squashfsgetparent Syzkaller reports a "KMSAN: uninit-value in squashfsgetparent" bug. This is caused by openbyhandleat() being called with a file handle containing an invalid parent inode number. In particular the inode number is that of a symbolic link, rather than a directory. Squashfsgetparent() gets called with that symbolic link inode, and accesses the parent member field. unsigned int parentino = squashfsi(inode)->parent; Because non-directory inodes in Squashfs do not have a parent value, this is uninitialised, and this causes an uninitialised value access. The fix is to initialise parent with the invalid inode 0, which will cause an EINVAL error to be returned. Regular inodes used to share the parent field with the blocklist_start field. This is removed in this commit to enable the parent field to contain the invalid inode number 0.