Re: [PATCH 4.19 012/168] crypto: ccree - fix resource leak on error path

Pavel Machek
2020-08-18T09:22:36Z

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Hi!

> Fix a small resource leak on the error path of cipher processing.

I believe this one is wrong.

> @@ -149,10 +148,19 @@ static int cc_cipher_init(struct crypto_tfm *tfm)
> ctx_p->flow_mode = cc_alg->flow_mode;
> ctx_p->drvdata = cc_alg->drvdata;
>
> + if (ctx_p->cipher_mode == DRV_CIPHER_ESSIV) {
> + /* Alloc hash tfm for essiv */
> + ctx_p->shash_tfm = crypto_alloc_shash("sha256-generic", 0, 0);
> + if (IS_ERR(ctx_p->shash_tfm)) {
> + dev_err(dev, "Error allocating hash tfm for ESSIV.\n");
> + return PTR_ERR(ctx_p->shash_tfm);
> + }
> + }

shash_tfm() is only allocated conditionally.

> +free_key:
> + kfree(ctx_p->user.key);
> +free_shash:
> + crypto_free_shash(ctx_p->shash_tfm);

But it is freed unconditionally, and free_shash() is not robust
against NULL pointer due to undefined behaviour in crypto_shash_tfm.

Additionally, it would be cleaner to set ctx_p->shash_tfm to NULL in
this path.

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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