Patch "crypto: aesni - handle zero length dst buffer" has been added to the 4.14-stable tree

Patch "crypto: aesni - handle zero length dst buffer" has been added to the 4.14-stable tree

[gregkh]

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

    crypto: aesni - handle zero length dst buffer

to the 4.14-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-aesni-handle-zero-length-dst-buffer.patch
and it can be found in the queue-4.14 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 9c674e1e2f9e24fa4392167efe343749008338e0 Mon Sep 17 00:00:00 2001
From: Stephan Mueller <smueller@chronox.de>
Date: Thu, 18 Jan 2018 20:41:09 +0100
Subject: crypto: aesni - handle zero length dst buffer

From: Stephan Mueller <smueller@chronox.de>

commit 9c674e1e2f9e24fa4392167efe343749008338e0 upstream.

GCM can be invoked with a zero destination buffer. This is possible if
the AAD and the ciphertext have zero lengths and only the tag exists in
the source buffer (i.e. a source buffer cannot be zero). In this case,
the GCM cipher only performs the authentication and no decryption
operation.

When the destination buffer has zero length, it is possible that no page
is mapped to the SG pointing to the destination. In this case,
sg_page(req->dst) is an invalid access. Therefore, page accesses should
only be allowed if the req->dst->length is non-zero which is the
indicator that a page must exist.

This fixes a crash that can be triggered by user space via AF_ALG.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/crypto/aesni-intel_glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -823,7 +823,7 @@ static int gcmaes_decrypt(struct aead_re
 	if (sg_is_last(req->src) &&
 	    (!PageHighMem(sg_page(req->src)) ||
 	    req->src->offset + req->src->length <= PAGE_SIZE) &&
-	    sg_is_last(req->dst) &&
+	    sg_is_last(req->dst) && req->dst->length &&
 	    (!PageHighMem(sg_page(req->dst)) ||
 	    req->dst->offset + req->dst->length <= PAGE_SIZE)) {
 		one_entry_in_sg = 1;


Patches currently in stable-queue which might be from smueller@chronox.de are

queue-4.14/crypto-af_alg-whitelist-mask-and-type.patch
queue-4.14/crypto-aesni-handle-zero-length-dst-buffer.patch