[PATCH] tls: Check return value of get_cipher_desc in fill_sg_out

[PATCH] tls: Check return value of get_cipher_desc in fill_sg_out

[Wentao Liang]

The function get_cipher_desc() may return NULL if the cipher type is
invalid or unsupported. In fill_sg_out(), the return value is used
without any checks, which could lead to a NULL pointer dereference.

This patch adds a DEBUG_NET_WARN_ON_ONCE check to ensure that
cipher_desc is valid and offloadable before proceeding. This prevents
potential crashes and provides a clear warning in debug builds.

Fixes: 8db44ab26beb ("tls: rename tls_cipher_size_desc to tls_cipher_desc")
Cc: stable@vger.kernel.org # 6.6+
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 net/tls/tls_device_fallback.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tls/tls_device_fallback.c b/net/tls/tls_device_fallback.c
index f9e3d3d90dcf..0f93a0833ec2 100644
--- a/net/tls/tls_device_fallback.c
+++ b/net/tls/tls_device_fallback.c
@@ -306,6 +306,7 @@ static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
 {
 	const struct tls_cipher_desc *cipher_desc =
 		get_cipher_desc(tls_ctx->crypto_send.info.cipher_type);
+	DEBUG_NET_WARN_ON_ONCE(!cipher_desc || !cipher_desc->offloadable);
 
 	sg_set_buf(&sg_out[0], dummy_buf, sync_size);
 	sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
-- 
2.42.0.windows.2

Re: [PATCH] tls: Check return value of get_cipher_desc in fill_sg_out

[Markus Elfring]

…
> This patch adds a DEBUG_NET_WARN_ON_ONCE check …

See also:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.14-rc2#n94


Would you like to append parentheses to any function names?

Regards,
Markus

Re: [PATCH] tls: Check return value of get_cipher_desc in fill_sg_out

[Jakub Kicinski]

On Wed, 12 Feb 2025 10:53:50 +0800 Wentao Liang wrote:
> The function get_cipher_desc() may return NULL if the cipher type is
> invalid or unsupported. In fill_sg_out(), the return value is used
> without any checks, which could lead to a NULL pointer dereference.
> 
> This patch adds a DEBUG_NET_WARN_ON_ONCE check to ensure that
> cipher_desc is valid and offloadable before proceeding. This prevents
> potential crashes and provides a clear warning in debug builds.

Does not make any sense, the state is validated during configuration.
-- 
pw-bot: reject
pv-bot: llm