ext4: Check that external xattr value block is zero

Currently we don't support xattrs with values stored out of line. Check
for that in ext4_xattr_check_names() to make sure we never work with
such xattrs since not all the code counts with that resulting is possible
weird corruption issues.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 22d2ebcd1f09..f845cb7c6623 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -199,6 +199,8 @@ ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
         }
 
         while (!IS_LAST_ENTRY(entry)) {
+                if (entry->e_value_block != 0)
+                        return -EFSCORRUPTED;
                 if (entry->e_value_size != 0 &&
                     (value_start + le16_to_cpu(entry->e_value_offs) <
                      (void *)e + sizeof(__u32) ||