crypto: rsa-pkcs1pad - fix buffer overread in pkcs1pad_verify_complete()

Before checking whether the expected digest_info is present, we need to
check that there are enough bytes remaining.

Fixes: a49de377e051 ("crypto: Add hash param to pkcs1pad")
Cc: <stable@vger.kernel.org> # v4.6+
Cc: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index 6b556dd..9d80483 100644 (file)
--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -476,6 +476,8 @@ static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
        pos++;
 
        if (digest_info) {
+               if (digest_info->size > dst_len - pos)
+                       goto done;
                if (crypto_memneq(out_buf + pos, digest_info->data,
                                  digest_info->size))
                        goto done;