| From | Ben Hutchings <> | Date | Thu, 28 Dec 2017 17:05:44 +0000 | Subject | [PATCH 3.16 098/204] crypto: shash - Fix zero-length shash ahash digest crash |
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3.16.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Herbert Xu <herbert@gondor.apana.org.au>
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@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Stephan Müller <smueller@chronox.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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));
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