* Re: [PATCH] drbd: correctly handling failed crypto_alloc_hash
2016-02-16 2:26 [PATCH] drbd: correctly handling failed crypto_alloc_hash Insu Yun
@ 2016-02-16 9:08 ` Lars Ellenberg
0 siblings, 0 replies; 2+ messages in thread
From: Lars Ellenberg @ 2016-02-16 9:08 UTC (permalink / raw)
To: Insu Yun
Cc: philipp.reisner, drbd-dev, linux-kernel, taesoo, yeongjin.jang,
insu, changwoo
On Mon, Feb 15, 2016 at 09:26:25PM -0500, Insu Yun wrote:
> crypto_alloc_hash returns an error code, not NULL.
You are correct, of course. Was broken since its introduction
five years ago. Strange though, we have a helper function further
down in that file, and other, even much older, call sites as well,
which are doing the IS_ERR() correctly.
Apparently no-one ever requested a non-supported alg.
> Signed-off-by: Insu Yun <wuninsu@gmail.com>
> ---
> drivers/block/drbd/drbd_receiver.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
> index 1957fe8..9063462 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -3403,7 +3403,7 @@ static int receive_protocol(struct drbd_connection *connection, struct packet_in
> */
>
> peer_integrity_tfm = crypto_alloc_hash(integrity_alg, 0, CRYPTO_ALG_ASYNC);
> - if (!peer_integrity_tfm) {
> + if (IS_ERR(peer_integrity_tfm)) {
> drbd_err(connection, "peer data-integrity-alg %s not supported\n",
> integrity_alg);
> goto disconnect;
Your patch is incomplete, though:
the first action in the "disconnect" cleanup path is
crypto_free_hash(peer_integrity_tfm);
so we better make sure it is not trying to free an error pointer:
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index c097909..6054c53 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -3376,7 +3376,8 @@ static int receive_protocol(struct drbd_connection *connection, struct packet_in
*/
peer_integrity_tfm = crypto_alloc_hash(integrity_alg, 0, CRYPTO_ALG_ASYNC);
- if (!peer_integrity_tfm) {
+ if (IS_ERR(peer_integrity_tfm)) {
+ peer_integrity_tfm = NULL;
drbd_err(connection, "peer data-integrity-alg %s not supported\n",
integrity_alg);
goto disconnect;
Thanks,
Lars
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