From: Eric Biggers <ebiggers@google.com>
Date: Mon, 6 Nov 2017 02:30:46 +0000 (-0800)
Subject: crypto: dh - Don't permit 'key' or 'g' size longer than 'p'
X-Git-Tag: v4.14.1~28
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5e56be0e260cc367d2eb1823a9b476d018d80152;p=platform%2Fkernel%2Flinux-exynos.git

crypto: dh - Don't permit 'key' or 'g' size longer than 'p'

commit ccd9888f14a8019c0bbdeeae758aba1f58693712 upstream.

The "qat-dh" DH implementation assumes that 'key' and 'g' can be copied
into a buffer with size 'p_size'.  However it was never checked that
that was actually the case, which most likely allowed users to cause a
buffer underflow via KEYCTL_DH_COMPUTE.

Fix this by updating crypto_dh_decode_key() to verify this precondition
for all DH implementations.

Fixes: c9839143ebbf ("crypto: qat - Add DH support")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c
index 708ae20..7f00c77 100644
--- a/crypto/dh_helper.c
+++ b/crypto/dh_helper.c
@@ -83,6 +83,14 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
 	if (secret.len != crypto_dh_key_len(params))
 		return -EINVAL;
 
+	/*
+	 * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
+	 * some drivers assume otherwise.
+	 */
+	if (params->key_size > params->p_size ||
+	    params->g_size > params->p_size)
+		return -EINVAL;
+
 	/* Don't allocate memory. Set pointers to data within
 	 * the given buffer
 	 */