Commit 179b1415 authored by Baokun Li's avatar Baokun Li Committed by Theodore Ts'o
Browse files

ext4: add EXT4_INODE_HAS_XATTR_SPACE macro in xattr.h 



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: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarRitesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220616021358.2504451-2-libaokun1@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 7f0d8e1d

fs/ext4/xattr.h

+13 −0
Original line number Diff line number Diff line
@@ -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;