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[v2,05/11] crypto: ecdh - fix ecdh_max_size

Message ID 1495033238-26016-6-git-send-email-tudor.ambarus@microchip.com (mailing list archive)
State Changes Requested
Delegated to: Herbert Xu
Headers show

Commit Message

Tudor Ambarus May 17, 2017, 3 p.m. UTC 
The function should return minimum size for output buffer
or error code if key hasn't been set.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 crypto/ecdh.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/crypto/ecdh.c b/crypto/ecdh.c
index c1f0163..830dfb6 100644
--- a/crypto/ecdh.c
+++ b/crypto/ecdh.c
@@ -107,10 +107,10 @@  static int ecdh_compute_value(struct kpp_request *req)
 static int ecdh_max_size(struct crypto_kpp *tfm)
 {
 	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
-	int nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
 
-	/* Public key is made of two coordinates */
-	return 2 * nbytes;
+	/* Public key is made of two coordinates, add one to the left shift  */
+	return ctx->ndigits ? ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1) :
+			      -EINVAL;
 }
 
 static void no_exit_tfm(struct crypto_kpp *tfm)