[PATCH 4.12 15/31] crypto: authencesn - Fix digest_null crash

Greg Kroah-Hartman
2017-08-03T23:20:37Z

From: Herbert Xu <herbert@gondor.apana.org.au>

commit 41cdf7a45389e01991ee31e3301ed83cb3e3f7dc upstream.

When authencesn is used together with digest_null a crash will
occur on the decrypt path. This is because normally we perform
a special setup to preserve the ESN, but this is skipped if there
is no authentication. However, on the post-authentication path
it always expects the preservation to be in place, thus causing
a crash when digest_null is used.

This patch fixes this by also skipping the post-processing when
there is no authentication.

Fixes: 104880a6b470 ("crypto: authencesn - Convert to new AEAD...")
Reported-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/authencesn.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/crypto/authencesn.c
+++ b/crypto/authencesn.c
@@ -248,6 +248,9 @@ static int crypto_authenc_esn_decrypt_ta
u8 *ihash = ohash + crypto_ahash_digestsize(auth);
u32 tmp[2];

+ if (!authsize)
+ goto decrypt;
+
/* Move high-order bits of sequence number back. */
scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
@@ -256,6 +259,8 @@ static int crypto_authenc_esn_decrypt_ta
if (crypto_memneq(ihash, ohash, authsize))
return -EBADMSG;

+decrypt:
+
sg_init_table(areq_ctx->dst, 2);
dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);