Patch "crypto: skcipher - Copy iv from desc even for 0-len walks" has been added to the 4.3-stable tree

This is a note to let you know that I've just added the patch titled

crypto: skcipher - Copy iv from desc even for 0-len walks

to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
crypto-skcipher-copy-iv-from-desc-even-for-0-len-walks.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Jason A. Donenfeld" <[email protected]>
Date: Sun, 6 Dec 2015 02:51:37 +0100
Subject: crypto: skcipher - Copy iv from desc even for 0-len walks

From: "Jason A. Donenfeld" <[email protected]>

commit 70d906bc17500edfa9bdd8c8b7e59618c7911613 upstream.

Some ciphers actually support encrypting zero length plaintexts. For example, many AEAD modes support this. The resulting ciphertext for those winds up being only the authentication tag, which is a result of the key, the iv, the additional data, and the fact that the plaintext had zero length. The blkcipher constructors won't copy the IV to the right place, however, when using a zero length input, resulting in some significant problems when ciphers call their initialization routines, only to find that the ->iv parameter is uninitialized. One such example of this would be using chacha20poly1305 with a zero length input, which then calls chacha20, which calls the key setup routine, which eventually OOPSes due to the uninitialized ->iv member.

---
 crypto/ablkcipher.c |    2 +-
 crypto/blkcipher.c  |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

@@ -277,12 +277,12 @@ static int ablkcipher_walk_first(struct
 	if (WARN_ON_ONCE(in_irq()))
 		return -EDEADLK;
 
+	walk->iv = req->info;
 	walk->nbytes = walk->total;
 	if (unlikely(!walk->total))
 		return 0;
 
 	walk->iv_buffer = NULL;
-	walk->iv = req->info;
 	if (unlikely(((unsigned long)walk->iv & alignmask))) {
 		int err = ablkcipher_copy_iv(walk, tfm, alignmask);
 

@@ -326,12 +326,12 @@ static int blkcipher_walk_first(struct b
 	if (WARN_ON_ONCE(in_irq()))
 		return -EDEADLK;
 
+	walk->iv = desc->info;
 	walk->nbytes = walk->total;
 	if (unlikely(!walk->total))
 		return 0;
 
 	walk->buffer = NULL;
-	walk->iv = desc->info;
 	if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
 		int err = blkcipher_copy_iv(walk);
 		if (err)

Patches currently in stable-queue which might be from [email protected] are

queue-4.3/crypto-skcipher-copy-iv-from-desc-even-for-0-len-walks.patch