eCryptfs: parse_tag_3_packet check tag 3 packet encrypted key size

The parse_tag_3_packet function does not check if the tag 3 packet contains a
encrypted key size larger than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES.

Signed-off-by: Ramon de Carvalho Valle <ramon@risesecurity.org>
[tyhicks@linux.vnet.ibm.com: Added printk newline and changed goto to out_free]
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Cc: stable@kernel.org (2.6.27 and 30)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 5414253d4c97..259525c9abb8 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -1303,6 +1303,13 @@ parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
         }
         (*new_auth_tok)->session_key.encrypted_key_size =
                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
+        if ((*new_auth_tok)->session_key.encrypted_key_size
+            > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
+                printk(KERN_WARNING "Tag 3 packet contains key larger "
+                       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
+                rc = -EINVAL;
+                goto out_free;
+        }
         if (unlikely(data[(*packet_size)++] != 0x04)) {
                 printk(KERN_WARNING "Unknown version number [%d]\n",
                        data[(*packet_size) - 1]);