ext4: don't read out of bounds when checking for in-inode xattrs
With i_extra_isize equal to or close to the available space, it was
possible for us to read past the end of the inode when trying to detect
or validate in-inode xattrs. Fix this by checking for the needed extra
space first.
This patch shouldn't have any noticeable effect on
non-corrupted/non-malicious filesystems.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e3e1978..59a518a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4527,7 +4527,9 @@ static inline void ext4_iget_extra_inode(struct inode *inode,
{
__le32 *magic = (void *)raw_inode +
EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
- if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
+ if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=
+ EXT4_INODE_SIZE(inode->i_sb) &&
+ *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
ext4_set_inode_state(inode, EXT4_STATE_XATTR);
ext4_find_inline_data_nolock(inode);
} else