3.16.61-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Eric Biggers <[email protected]> commit 290ab230016f187c3551d8380ea742889276d03a upstream. With i_extra_isize equal to or close to the available space, it was possible for us to read past the end of the inode when trying to detect or validate in-inode xattrs. Fix this by checking for the needed extra space first. This patch shouldn't have any noticeable effect on non-corrupted/non-malicious filesystems. Signed-off-by: Eric Biggers <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]> Reviewed-by: Andreas Dilger <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- fs/ext4/inode.c | 4 +++- fs/ext4/xattr.c | 5 ++--- 2 files changed, 5 insertions(+), 4 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4165,7 +4165,9 @@ static inline void ext4_iget_extra_inode { __le32 *magic = (void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize; - if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) { + if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <= + EXT4_INODE_SIZE(inode->i_sb) && + *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) { ext4_set_inode_state(inode, EXT4_STATE_XATTR); ext4_find_inline_data_nolock(inode); } else --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -247,13 +247,12 @@ static int __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, void *end, const char *function, unsigned int line) { - struct ext4_xattr_entry *entry = IFIRST(header); int error = -EIO; - if (((void *) header >= end) || + if (end - (void *)header < sizeof(*header) + sizeof(u32) || (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC))) goto errout; - error = ext4_xattr_check_names(entry, end, entry); + error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header)); errout: if (error) __ext4_error_inode(inode, function, line, 0,
