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authorEric Biggers <ebiggers@google.com>2017-06-08 14:48:18 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-02-16 20:09:38 +0100
commit33813d43dd593e1c32c567c75483233212b825ae (patch)
treece8ee721b907a2b31745349f74260d396a415115 /security
parent4f8a4e9984479c05bbf78f09e1744711a3eb32b3 (diff)
KEYS: encrypted: fix buffer overread in valid_master_desc()
commit 794b4bc292f5d31739d89c0202c54e7dc9bc3add upstream. With the 'encrypted' key type it was possible for userspace to provide a data blob ending with a master key description shorter than expected, e.g. 'keyctl add encrypted desc "new x" @s'. When validating such a master key description, validate_master_desc() could read beyond the end of the buffer. Fix this by using strncmp() instead of memcmp(). [Also clean up the code to deduplicate some logic.] Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Jin Qian <jinqian@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/keys/encrypted-keys/encrypted.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
index ce295c0c1da0..e44e844c8ec4 100644
--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const char *ecryptfs_desc)
*/
static int valid_master_desc(const char *new_desc, const char *orig_desc)
{
- if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
- if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
- goto out;
- if (orig_desc)
- if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
- goto out;
- } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
- if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
- goto out;
- if (orig_desc)
- if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
- goto out;
- } else
- goto out;
+ int prefix_len;
+
+ if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
+ prefix_len = KEY_TRUSTED_PREFIX_LEN;
+ else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
+ prefix_len = KEY_USER_PREFIX_LEN;
+ else
+ return -EINVAL;
+
+ if (!new_desc[prefix_len])
+ return -EINVAL;
+
+ if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
+ return -EINVAL;
+
return 0;
-out:
- return -EINVAL;
}
/*