ubifs: Check data node size before truncate

commit 95a22d2084d72ea067d8323cc85677dba5d97cae upstream.

Check whether the size is within bounds before using it.
If the size is not correct, abort and dump the bad data node.

Cc: Kees Cook <keescook@chromium.org>
Cc: Silvio Cesare <silvio.cesare@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 1e51764a3c2ac ("UBIFS: add new flash file system")
Reported-by: Silvio Cesare <silvio.cesare@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index da8afdfccaa64daa357dfc969c50d341783efab5..eea12d25a58b7c4dc30ef5cac3b91122d9996990 100644 (file)
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1387,7 +1387,16 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,
                else if (err)
                        goto out_free;
                else {
-                       if (le32_to_cpu(dn->size) <= dlen)
+                       int dn_len = le32_to_cpu(dn->size);
+
+                       if (dn_len <= 0 || dn_len > UBIFS_BLOCK_SIZE) {
+                               ubifs_err(c, "bad data node (block %u, inode %lu)",
+                                         blk, inode->i_ino);
+                               ubifs_dump_node(c, dn);
+                               goto out_free;
+                       }
+
+                       if (dn_len <= dlen)
                                dlen = 0; /* Nothing to do */
                        else {
                                err = truncate_data_node(c, inode, blk, dn, &dlen);