linux-kernel - Re: [PATCH 1/5] selftests/sgx: Fix uninitialized pointer dereference in error path.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <30cdc29283a6ed6ece205d9a91f44b44b2b3a73c.camel@intel.com>
Date:   Thu, 3 Aug 2023 03:51:36 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Van Bulck, Jo" <jo.vanbulck@...kuleuven.be>
CC:     "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH 1/5] selftests/sgx: Fix uninitialized pointer dereference
 in error path.

On Mon, 2023-07-24 at 18:58 +0200, Jo Van Bulck wrote:
> Ensure ctx is zero-initialized, such that the encl_measure function will
> not call EVP_MD_CTX_destroy with an uninitialized ctx pointer in case of an
> early error during key generation.
> 
> Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
> ---
>  tools/testing/selftests/sgx/sigstruct.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c
> index a07896a46364..dd1fdab90e26 100644
> --- a/tools/testing/selftests/sgx/sigstruct.c
> +++ b/tools/testing/selftests/sgx/sigstruct.c
> @@ -318,9 +318,9 @@ bool encl_measure(struct encl *encl)
>  	struct sgx_sigstruct *sigstruct = &encl->sigstruct;
>  	struct sgx_sigstruct_payload payload;
>  	uint8_t digest[SHA256_DIGEST_LENGTH];
> +	EVP_MD_CTX *ctx = NULL;
>  	unsigned int siglen;
>  	RSA *key = NULL;
> -	EVP_MD_CTX *ctx;
>  	int i;
>  
>  	memset(sigstruct, 0, sizeof(*sigstruct));

Is it safe to assume EVP_MD_CTX_destroy() can always handle a NULL ctx?

The manpage says:

EVP_MD_CTX_destroy() cleans up digest context ctx and frees up the space
allocated to it, it should be called only on a context created using
EVP_MD_CTX_create().