If there is a corupted file system where the claimed depth of the extent tree is -1, this can cause a massive buffer overrun leading to sadness. https://bugzilla.kernel.org/show_bug.cgi?id=199417 Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> --- fs/ext4/ext4_extents.h | 1 + fs/ext4/extents.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h index 98fb0c119c68..adf6668b596f 100644 --- a/fs/ext4/ext4_extents.h +++ b/fs/ext4/ext4_extents.h @@ -91,6 +91,7 @@ struct ext4_extent_header { }; #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) +#define EXT4_MAX_EXTENT_DEPTH 5 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ (sizeof(struct ext4_extent_header) + \ diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index c969275ce3ee..08226f72b7ee 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -869,6 +869,12 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block, eh = ext_inode_hdr(inode); depth = ext_depth(inode); + if (depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) { + EXT4_ERROR_INODE(inode, "inode has invalid extent depth: %d", + depth); + ret = -EFSCORRUPTED; + goto err; + } if (path) { ext4_ext_drop_refs(path); -- 2.18.0.rc0
