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| author | Eric Biggers <ebiggers@google.com> | 2016-12-01 14:43:33 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-12-01 14:43:33 -0500 |
| commit | 2dc8d9e19b0d891b0d3675b5ac82be9be3875e36 (patch) | |
| tree | 04d4cf3d3be395178b1d5553e2191d8b4c5da1eb /fs/ext4 | |
| parent | ba679017ef0f47d31c50df731441fdd39bf4bf13 (diff) | |
| download | linux-2dc8d9e19b0d891b0d3675b5ac82be9be3875e36.tar.gz linux-2dc8d9e19b0d891b0d3675b5ac82be9be3875e36.tar.bz2 linux-2dc8d9e19b0d891b0d3675b5ac82be9be3875e36.zip | |
ext4: forbid i_extra_isize not divisible by 4
i_extra_isize not divisible by 4 is problematic for several reasons:
- It causes the in-inode xattr space to be misaligned, but the xattr
header and entries are not declared __packed to express this
possibility. This may cause poor performance or incorrect code
generation on some platforms.
- When validating the xattr entries we can read past the end of the
inode if the size available for xattrs is not a multiple of 4.
- It allows the nonsensical i_extra_isize=1, which doesn't even leave
enough room for i_extra_isize itself.
Therefore, update ext4_iget() to consider i_extra_isize not divisible by
4 to be an error, like the case where i_extra_isize is too large.
This also matches the rule recently added to e2fsck for determining
whether an inode has valid i_extra_isize.
This patch shouldn't have any noticeable effect on
non-corrupted/non-malicious filesystems, since the size of ext4_inode
has always been a multiple of 4.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/inode.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b48ca0392b9c..e3e197898c66 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4572,10 +4572,12 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) { ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize); if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > - EXT4_INODE_SIZE(inode->i_sb)) { - EXT4_ERROR_INODE(inode, "bad extra_isize (%u != %u)", - EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize, - EXT4_INODE_SIZE(inode->i_sb)); + EXT4_INODE_SIZE(inode->i_sb) || + (ei->i_extra_isize & 3)) { + EXT4_ERROR_INODE(inode, + "bad extra_isize %u (inode size %u)", + ei->i_extra_isize, + EXT4_INODE_SIZE(inode->i_sb)); ret = -EFSCORRUPTED; goto bad_inode; } @@ -4693,6 +4695,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) { if (ei->i_extra_isize == 0) { /* The extra space is currently unused. Use it. */ + BUILD_BUG_ON(sizeof(struct ext4_inode) & 3); ei->i_extra_isize = sizeof(struct ext4_inode) - EXT4_GOOD_OLD_INODE_SIZE; } else { |