ext4: do not allow external inodes for inline data

commit 117166efb1ee8f13c38f9e96b258f16d4923f888 upstream.

The inline data feature was implemented before we added support for
external inodes for xattrs.  It makes no sense to support that
combination, but the problem is that there are a number of extended
attribute checks that are skipped if e_value_inum is non-zero.

Unfortunately, the inline data code is completely e_value_inum
unaware, and attempts to interpret the xattr fields as if it were an
inline xattr --- at which point, Hilarty Ensues.

This addresses CVE-2018-11412.

https://bugzilla.kernel.org/show_bug.cgi?id=199803

Reported-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Fixes: e50e5129f384 ("ext4: xattr-in-inode support")
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index fd9501977f1c7a5d9db13ab9241f9efe6ee47962..8f5dc243effd7649b0e5c2382edb95128a7bd447 100644 (file)
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -150,6 +150,12 @@ int ext4_find_inline_data_nolock(struct inode *inode)
                goto out;
 
        if (!is.s.not_found) {
+               if (is.s.here->e_value_inum) {
+                       EXT4_ERROR_INODE(inode, "inline data xattr refers "
+                                        "to an external xattr inode");
+                       error = -EFSCORRUPTED;
+                       goto out;
+               }
                EXT4_I(inode)->i_inline_off = (u16)((void *)is.s.here -
                                        (void *)ext4_raw_inode(&is.iloc));
                EXT4_I(inode)->i_inline_size = EXT4_MIN_INLINE_DATA_SIZE +