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

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: c983914 ("crypto: qat - Add DH support") Cc: <[email protected]> # v4.8+ Signed-off-by: Eric Biggers <[email protected]> Reviewed-by: Tudor Ambarus <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
ambv · Nov 10, 2017 · ccd9888 · ccd9888
1 parent 199512b
commit ccd9888
Showing 1 changed file with 8 additions and 0 deletions.
diff --git 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
 	 */