This is a note to let you know that I've just added the patch titled
KEYS: encrypted: fix buffer overread in valid_master_desc()
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: keys-encrypted-fix-buffer-overread-in-valid_master_desc.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 794b4bc292f5d31739d89c0202c54e7dc9bc3add Mon Sep 17 00:00:00 2001
From: Eric Biggers ebiggers@google.com Date: Thu, 8 Jun 2017 14:48:18 +0100 Subject: KEYS: encrypted: fix buffer overread in valid_master_desc()
From: Eric Biggers ebiggers@google.com
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
--- security/keys/encrypted-keys/encrypted.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-)
--- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const cha */ 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; }
/*
Patches currently in stable-queue which might be from ebiggers@google.com are
queue-4.9/keys-encrypted-fix-buffer-overread-in-valid_master_desc.patch