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While fuzz testing JFS with ASAN enabled an OOB read was detected in grub_jfs_opendir(). The issue occurred due to an invalid directory slot index in the first entry of the sorted directory slot array in the inode directory header. The fix ensures the slot index is validated before accessing it. Given that an internal or a leaf node in a directory B+ tree is a 4 KiB in size and each directory slot is always 32 bytes, the max number of slots in a node is 128. The validation ensures that the slot index doesn't exceed this limit. [1] https://jfs.sourceforge.net/project/pub/jfslayout.pdf JFS will allocate 4K of disk space for an internal node of the B+ tree. An internal node looks the same as a leaf node. - page 10 Fixed number of Directory Slots depending on the size of the node. These are the slots to be used for storing the directory slot array and the directory entries or router entries. A directory slot is always 32 bytes. ... A Directory Slot Array which is a sorted array of indices to the directory slots that are currently in use. ... An internal or a leaf node in the directory B+ tree is a 4K page. - page 25 Signed-off-by: Lidong Chen <lidong.chen@oracle.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'