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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 0cabf2af6f5ac3c88cb106c4e06087a5a39b8e1e Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sat, 7 Oct 2017 11:29:48 +0800
Subject: crypto: skcipher - Fix crash on zero-length input
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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From: Herbert Xu <herbert@gondor.apana.org.au>

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.

Fixes: b286d8b1a690 ("crypto: skcipher - Add skcipher walk...")
Reported-by: Stephan Müller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -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 herbert@gondor.apana.org.au 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