From: Baokun Li <libaokun1@xxxxxxxxxx> commit 179b14152dcb6a24c3415200603aebca70ff13af upstream. When adding an xattr to an inode, we must ensure that the inode_size is not less than EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad. Otherwise, the end position may be greater than the start position, resulting in UAF. Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> Link: https://lore.kernel.org/r/20220616021358.2504451-2-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/xattr.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -95,6 +95,19 @@ struct ext4_xattr_entry { #define EXT4_ZERO_XATTR_VALUE ((void *)-1) +/* + * If we want to add an xattr to the inode, we should make sure that + * i_extra_isize is not 0 and that the inode size is not less than + * EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad. + * EXT4_GOOD_OLD_INODE_SIZE extra_isize header entry pad data + * |--------------------------|------------|------|---------|---|-------| + */ +#define EXT4_INODE_HAS_XATTR_SPACE(inode) \ + ((EXT4_I(inode)->i_extra_isize != 0) && \ + (EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize + \ + sizeof(struct ext4_xattr_ibody_header) + EXT4_XATTR_PAD <= \ + EXT4_INODE_SIZE((inode)->i_sb))) + struct ext4_xattr_info { const char *name; const void *value;
