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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: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220616021358.2504451-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2022-06-16 10:13:55 +08:00 committed by Theodore Ts'o
parent 7f0d8e1d60
commit 179b14152d
1 changed files with 13 additions and 0 deletions
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13
fs/ext4/xattr.h
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@ -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;