Patch "crypto: arm64/aes-ctr - fix NULL dereference in tail processing" has been added to the 4.4-stable tree

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

crypto: arm64/aes-ctr - fix NULL dereference in tail processing

to the 4.4-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-arm64-aes-ctr-fix-null-dereference-in-tail-processing.patch
and it can be found in the queue-4.4 subdirectory.

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

From: Ard Biesheuvel <[email protected]>
Date: Tue, 13 Sep 2016 09:48:53 +0100
Subject: crypto: arm64/aes-ctr - fix NULL dereference in tail processing

From: Ard Biesheuvel <[email protected]>

commit 2db34e78f126c6001d79d3b66ab1abb482dc7caa upstream.

The AES-CTR glue code avoids calling into the blkcipher API for the tail portion of the walk, by comparing the remainder of walk.nbytes modulo AES_BLOCK_SIZE with the residual nbytes, and jumping straight into the tail processing block if they are equal. This tail processing block checks whether nbytes != 0, and does nothing otherwise.

However, in case of an allocation failure in the blkcipher layer, we may enter this code with walk.nbytes == 0, while nbytes > 0. In this case, we should not dereference the source and destination pointers, since they may be NULL. So instead of checking for nbytes != 0, check for (walk.nbytes % AES_BLOCK_SIZE) != 0, which implies the former in non-error conditions.

---
 arch/arm64/crypto/aes-glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -211,7 +211,7 @@ static int ctr_encrypt(struct blkcipher_
 		err = blkcipher_walk_done(desc, &walk,
 					  walk.nbytes % AES_BLOCK_SIZE);
 	}
-	if (nbytes) {
+	if (walk.nbytes % AES_BLOCK_SIZE) {
 		u8 *tdst = walk.dst.virt.addr + blocks * AES_BLOCK_SIZE;
 		u8 *tsrc = walk.src.virt.addr + blocks * AES_BLOCK_SIZE;
 		u8 __aligned(8) tail[AES_BLOCK_SIZE];

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

queue-4.4/crypto-arm64-aes-ctr-fix-null-dereference-in-tail-processing.patch queue-4.4/crypto-arm-aes-ctr-fix-null-dereference-in-tail-processing.patch queue-4.4/crypto-skcipher-fix-blkcipher-walk-oom-crash.patch