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Commit b61907bb authored by Herbert Xu's avatar Herbert Xu
Browse files

crypto: shash - Fix zero-length shash ahash digest crash 



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.

Cc: <stable@vger.kernel.org>
Reported-by: default avatarStephan <Müller&lt;smueller@chronox.de>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Tested-by: default avatarStephan Müller <smueller@chronox.de>
parent 0cabf2af

crypto/shash.c

+5 −3
Original line number Diff line number Diff line
@@ -275,12 +275,14 @@ static int shash_async_finup(struct ahash_request *req) 


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));