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authorEric Biggers <ebiggers@google.com>2016-12-01 14:43:33 -0500
committerTheodore Ts'o <tytso@mit.edu>2016-12-01 14:43:33 -0500
commit2dc8d9e19b0d891b0d3675b5ac82be9be3875e36 (patch)
tree04d4cf3d3be395178b1d5553e2191d8b4c5da1eb /fs/ext4
parentba679017ef0f47d31c50df731441fdd39bf4bf13 (diff)
downloadlinux-2dc8d9e19b0d891b0d3675b5ac82be9be3875e36.tar.bz2
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.c11
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 {