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SubjectRe: crypto: slab-out-of-bounds in skcipher_recvmsg
On Fri, Jan 15, 2016 at 07:22:04PM +0100, Dmitry Vyukov wrote:
> Hello,
>
> The following program causes slab-out-of-bounds in skcipher_recvmsg:

Thanks for the report. This patch should fix it.

---8<---
Subject: crypto: algif_skcipher - Load TX SG list after waiting

We need to load the TX SG list in sendmsg(2) after waiting for
incoming data, not before.

Cc: stable@vger.kernel.org
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index dfff8b0..df86fb4 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -647,13 +647,6 @@ static int skcipher_recvmsg_sync(struct socket *sock, struct msghdr *msg,

lock_sock(sk);
while (msg_data_left(msg)) {
- sgl = list_first_entry(&ctx->tsgl,
- struct skcipher_sg_list, list);
- sg = sgl->sg;
-
- while (!sg->length)
- sg++;
-
if (!ctx->used) {
err = skcipher_wait_for_data(sk, flags);
if (err)
@@ -674,6 +667,13 @@ static int skcipher_recvmsg_sync(struct socket *sock, struct msghdr *msg,
if (!used)
goto free;

+ sgl = list_first_entry(&ctx->tsgl,
+ struct skcipher_sg_list, list);
+ sg = sgl->sg;
+
+ while (!sg->length)
+ sg++;
+
skcipher_request_set_crypt(&ctx->req, sg, ctx->rsgl.sg, used,
ctx->iv);

--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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