This is a note to let you know that I've just added the patch titled crypto: shash - Fix zero-length shash ahash digest crash to the 4.9-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-shash-fix-zero-length-shash-ahash-digest-crash.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b61907bb42409adf9b3120f741af7c57dd7e3db2 Mon Sep 17 00:00:00 2001 From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Date: Mon, 9 Oct 2017 23:30:02 +0800 Subject: crypto: shash - Fix zero-length shash ahash digest crash MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> commit b61907bb42409adf9b3120f741af7c57dd7e3db2 upstream. The shash ahash digest adaptor function may crash if given a zero-length input together with a null SG list. This is because it tries to read the SG list before looking at the length. This patch fixes it by checking the length first. Reported-by: Stephan Müller<smueller@xxxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Tested-by: Stephan Müller <smueller@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- crypto/shash.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/crypto/shash.c +++ b/crypto/shash.c @@ -274,12 +274,14 @@ static int shash_async_finup(struct ahas int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc) { - struct scatterlist *sg = req->src; - unsigned int offset = sg->offset; unsigned int nbytes = req->nbytes; + struct scatterlist *sg; + unsigned int offset; int err; - if (nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset)) { + if (nbytes && + (sg = req->src, offset = sg->offset, + nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset))) { void *data; data = kmap_atomic(sg_page(sg)); Patches currently in stable-queue which might be from herbert@xxxxxxxxxxxxxxxxxxx are queue-4.9/crypto-shash-fix-zero-length-shash-ahash-digest-crash.patch