From: Herbert Xu Date: Mon, 9 Oct 2017 15:30:02 +0000 (+0800) Subject: crypto: shash - Fix zero-length shash ahash digest crash X-Git-Tag: v4.4.93~18 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=03bd90fc82e4a0b39455de5a9a7a75a7a9a7e662;p=profile%2Fcommon%2Fplatform%2Fkernel%2Flinux-artik7.git crypto: shash - Fix zero-length shash ahash digest crash 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 Signed-off-by: Herbert Xu Tested-by: Stephan Müller Signed-off-by: Greg Kroah-Hartman --- diff --git a/crypto/shash.c b/crypto/shash.c index 3597545..b2cd109 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -274,12 +274,14 @@ 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));