[PATCH net-next v2] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[PATCH net-next v2] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[Simon Horman]

Pass union tls_crypto_context pointer, rather than struct
tls_crypto_info pointer, to memzero_explicit().

The address of the pointer is the same before and after.
But the new construct means that the size of the dereferenced pointer type
matches the size being zeroed. Which aids static analysis.

As reported by Smatch:

  .../tls_main.c:842 do_tls_setsockopt_conf() error: memzero_explicit() 'crypto_info' too small (4 vs 56)

No functional change intended.
Compile tested only.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Simon Horman <horms@kernel.org>
---
Changes in v2:
- Added Reviewed-by tag from Przemek Kitszel
- Updated to use sizeof(*crypto_ctx), as suggested by Przemek Kitszel
- Link to v1: https://lore.kernel.org/r/20240705-tls-memzero-v1-1-0496871cfe9b@kernel.org
---
 net/tls/tls_main.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 90b7f253d363..6b4b9f2749a6 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -616,6 +616,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 	struct tls_crypto_info *alt_crypto_info;
 	struct tls_context *ctx = tls_get_ctx(sk);
 	const struct tls_cipher_desc *cipher_desc;
+	union tls_crypto_context *crypto_ctx;
 	int rc = 0;
 	int conf;
 
@@ -623,13 +624,15 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 		return -EINVAL;
 
 	if (tx) {
-		crypto_info = &ctx->crypto_send.info;
+		crypto_ctx = &ctx->crypto_send;
 		alt_crypto_info = &ctx->crypto_recv.info;
 	} else {
-		crypto_info = &ctx->crypto_recv.info;
+		crypto_ctx = &ctx->crypto_recv;
 		alt_crypto_info = &ctx->crypto_send.info;
 	}
 
+	crypto_info = &crypto_ctx->info;
+
 	/* Currently we don't support set crypto info more than one time */
 	if (TLS_CRYPTO_INFO_READY(crypto_info))
 		return -EBUSY;
@@ -710,7 +713,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 	return 0;
 
 err_crypto_info:
-	memzero_explicit(crypto_info, sizeof(union tls_crypto_context));
+	memzero_explicit(crypto_ctx, sizeof(*crypto_ctx));
 	return rc;
 }
 

Re: [PATCH net-next v2] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[Jakub Kicinski]

On Mon, 08 Jul 2024 08:27:19 +0100 Simon Horman wrote:
> Pass union tls_crypto_context pointer, rather than struct
> tls_crypto_info pointer, to memzero_explicit().
> 
> The address of the pointer is the same before and after.
> But the new construct means that the size of the dereferenced pointer type
> matches the size being zeroed. Which aids static analysis.
> 
> As reported by Smatch:
> 
>   .../tls_main.c:842 do_tls_setsockopt_conf() error: memzero_explicit() 'crypto_info' too small (4 vs 56)
> 
> No functional change intended.
> Compile tested only.
> 
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> Signed-off-by: Simon Horman <horms@kernel.org>

Reviewed-by: Jakub Kicinski <kuba@kernel.org>

Re: [PATCH net-next v2] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 08 Jul 2024 08:27:19 +0100 you wrote:
> Pass union tls_crypto_context pointer, rather than struct
> tls_crypto_info pointer, to memzero_explicit().
> 
> The address of the pointer is the same before and after.
> But the new construct means that the size of the dereferenced pointer type
> matches the size being zeroed. Which aids static analysis.
> 
> [...]

Here is the summary with links:
  - [net-next,v2] net: tls: Pass union tls_crypto_context pointer to memzero_explicit
    https://git.kernel.org/netdev/net-next/c/0d9e699d3421

You are awesome, thank you!
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