In the Linux kernel, the following vulnerability has been resolved:xfs: don't walk off the end of a directory data blockThis adds sanity checks for xfs_dir2_data_unused and xfs_dir2_data_entryto make sure don't stray beyond valid memory region. Before patching, theloop simply checks that the start offset of the dup and dep is within therange. So in a crafted image, if last entry is xfs_dir2_data_unused, wecan change dup->length to dup->length-1 and leave 1 byte of space. In thenext traversal, this space will be considered as dup or dep. We mayencounter an out of bound read when accessing the fixed members.In the patch, we make sure that the remaining bytes large enough to holdan unused entry before accessing xfs_dir2_data_unused andxfs_dir2_data_unused is XFS_DIR2_DATA_ALIGN byte aligned. We also makesure that the remaining bytes large enough to hold a dirent with asingle-byte name before accessing xfs_dir2_data_entry.
