Patch "crypto: skcipher - Fix crash on zero-length input" has been added to the 4.13-stable tree

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

crypto: skcipher - Fix crash on zero-length input

to the 4.13-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-fix-crash-on-zero-length-input.patch
and it can be found in the queue-4.13 subdirectory.

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

From: Herbert Xu <[email protected]>
Date: Sat, 7 Oct 2017 11:29:48 +0800
Subject: crypto: skcipher - Fix crash on zero-length input
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From: Herbert Xu <[email protected]>

commit 0cabf2af6f5ac3c88cb106c4e06087a5a39b8e1e upstream.

The skcipher walk interface doesn't handle zero-length input properly as the old blkcipher walk interface did. This is due to the fact that the length check is done too late.

This patch moves the length check forward so that it does the right thing.

---
 crypto/skcipher.c |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

@@ -426,14 +426,9 @@ static int skcipher_copy_iv(struct skcip
 
 static int skcipher_walk_first(struct skcipher_walk *walk)
 {
-	walk->nbytes = 0;
-
 	if (WARN_ON_ONCE(in_irq()))
 		return -EDEADLK;
 
-	if (unlikely(!walk->total))
-		return 0;
-
 	walk->buffer = NULL;
 	if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
 		int err = skcipher_copy_iv(walk);

@@ -452,10 +447,15 @@ static int skcipher_walk_skcipher(struct
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 
+	walk->total = req->cryptlen;
+	walk->nbytes = 0;
+
+	if (unlikely(!walk->total))
+		return 0;
+
 	scatterwalk_start(&walk->in, req->src);
 	scatterwalk_start(&walk->out, req->dst);
 
-	walk->total = req->cryptlen;
 	walk->iv = req->iv;
 	walk->oiv = req->iv;
 

@@ -509,6 +509,11 @@ static int skcipher_walk_aead_common(str
 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 	int err;
 
+	walk->nbytes = 0;
+
+	if (unlikely(!walk->total))
+		return 0;
+
 	walk->flags &= ~SKCIPHER_WALK_PHYS;
 
 	scatterwalk_start(&walk->in, req->src);

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

queue-4.13/crypto-skcipher-fix-crash-on-zero-length-input.patch queue-4.13/crypto-shash-fix-zero-length-shash-ahash-digest-crash.patch