[PATCH 5.3 086/105] crypto: atmel-aes - Fix IV handling when req->nbytes < ivsize

Greg Kroah-Hartman
2019-12-11T15:56:22Z

From: Tudor Ambarus <tudor.ambarus@microchip.com>

commit 86ef1dfcb561473fbf5e199d58d18c55554d78be upstream.

commit 394a9e044702 ("crypto: cfb - add missing 'chunksize' property")
adds a test vector where the input length is smaller than the IV length
(the second test vector). This revealed a NULL pointer dereference in
the atmel-aes driver, that is caused by passing an incorrect offset in
scatterwalk_map_and_copy() when atmel_aes_complete() is called.

Do not save the IV in req->info of ablkcipher_request (or equivalently
req->iv of skcipher_request) when req->nbytes < ivsize, because the IV
will not be further used.

While touching the code, modify the type of ivsize from int to
unsigned int, to comply with the return type of
crypto_ablkcipher_ivsize().

Fixes: 91308019ecb4 ("crypto: atmel-aes - properly set IV after {en,de}crypt")
Cc: <stable@vger.kernel.org>
Signed-off-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>

---
drivers/crypto/atmel-aes.c | 53 +++++++++++++++++++++++++--------------------
1 file changed, 30 insertions(+), 23 deletions(-)

--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -490,6 +490,29 @@ static inline bool atmel_aes_is_encrypt(
static void atmel_aes_authenc_complete(struct atmel_aes_dev *dd, int err);
#endif

+static void atmel_aes_set_iv_as_last_ciphertext_block(struct atmel_aes_dev *dd)
+{
+ struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
+ struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
+ struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
+ unsigned int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+
+ if (req->nbytes < ivsize)
+ return;
+
+ if (rctx->mode & AES_FLAGS_ENCRYPT) {
+ scatterwalk_map_and_copy(req->info, req->dst,
+ req->nbytes - ivsize, ivsize, 0);
+ } else {
+ if (req->src == req->dst)
+ memcpy(req->info, rctx->lastc, ivsize);
+ else
+ scatterwalk_map_and_copy(req->info, req->src,
+ req->nbytes - ivsize,
+ ivsize, 0);
+ }
+}
+
static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
{
#ifdef CONFIG_CRYPTO_DEV_ATMEL_AUTHENC
@@ -500,26 +523,8 @@ static inline int atmel_aes_complete(str
clk_disable(dd->iclk);
dd->flags &= ~AES_FLAGS_BUSY;

- if (!dd->ctx->is_aead) {
- struct ablkcipher_request *req =
- ablkcipher_request_cast(dd->areq);
- struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
- struct crypto_ablkcipher *ablkcipher =
- crypto_ablkcipher_reqtfm(req);
- int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
-
- if (rctx->mode & AES_FLAGS_ENCRYPT) {
- scatterwalk_map_and_copy(req->info, req->dst,
- req->nbytes - ivsize, ivsize, 0);
- } else {
- if (req->src == req->dst) {
- memcpy(req->info, rctx->lastc, ivsize);
- } else {
- scatterwalk_map_and_copy(req->info, req->src,
- req->nbytes - ivsize, ivsize, 0);
- }
- }
- }
+ if (!dd->ctx->is_aead)
+ atmel_aes_set_iv_as_last_ciphertext_block(dd);

if (dd->is_async)
dd->areq->complete(dd->areq, err);
@@ -1125,10 +1130,12 @@ static int atmel_aes_crypt(struct ablkci
rctx->mode = mode;

if (!(mode & AES_FLAGS_ENCRYPT) && (req->src == req->dst)) {
- int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+ unsigned int ivsize = crypto_ablkcipher_ivsize(ablkcipher);

- scatterwalk_map_and_copy(rctx->lastc, req->src,
- (req->nbytes - ivsize), ivsize, 0);
+ if (req->nbytes >= ivsize)
+ scatterwalk_map_and_copy(rctx->lastc, req->src,
+ req->nbytes - ivsize,
+ ivsize, 0);
}

return atmel_aes_handle_queue(dd, &req->base);