Re: [PATCH] crypto: virtio/akcipher - Fix stack overflow on memcpy

[Nathan Chancellor]

On Tue, Jan 30, 2024 at 07:27:40PM +0800, zhenwei pi wrote:
> sizeof(struct virtio_crypto_akcipher_session_para) is less than
> sizeof(struct virtio_crypto_op_ctrl_req::u), copying more bytes from
> stack variable leads stack overflow. Clang reports this issue by
> commands:
> make -j CC=clang-14 mrproper >/dev/null 2>&1
> make -j O=/tmp/crypto-build CC=clang-14 allmodconfig >/dev/null 2>&1
> make -j O=/tmp/crypto-build W=1 CC=clang-14 drivers/crypto/virtio/
>   virtio_crypto_akcipher_algs.o
> 
> Fixes: 59ca6c93387d ("virtio-crypto: implement RSA algorithm")
> Link: https://lore.kernel.org/all/0a194a79-e3a3-45e7-be98-83abd3e1cb7e@xxxxxxxxxxxx/
> Signed-off-by: zhenwei pi <pizhenwei@xxxxxxxxxxxxx>

I can confirm this resolves the warning for me as well.

Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> # build

I suspect Guenter should have a formal Reported-by tag. Should this be
CC'd for stable@ as well?

Cheers,
Nathan

> ---
>  drivers/crypto/virtio/virtio_crypto_akcipher_algs.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c
> index 2621ff8a9376..de53eddf6796 100644
> --- a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c
> +++ b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c
> @@ -104,7 +104,8 @@ static void virtio_crypto_dataq_akcipher_callback(struct virtio_crypto_request *
>  }
>  
>  static int virtio_crypto_alg_akcipher_init_session(struct virtio_crypto_akcipher_ctx *ctx,
> -		struct virtio_crypto_ctrl_header *header, void *para,
> +		struct virtio_crypto_ctrl_header *header,
> +		struct virtio_crypto_akcipher_session_para *para,
>  		const uint8_t *key, unsigned int keylen)
>  {
>  	struct scatterlist outhdr_sg, key_sg, inhdr_sg, *sgs[3];
> @@ -128,7 +129,7 @@ static int virtio_crypto_alg_akcipher_init_session(struct virtio_crypto_akcipher
>  
>  	ctrl = &vc_ctrl_req->ctrl;
>  	memcpy(&ctrl->header, header, sizeof(ctrl->header));
> -	memcpy(&ctrl->u, para, sizeof(ctrl->u));
> +	memcpy(&ctrl->u.akcipher_create_session.para, para, sizeof(*para));
>  	input = &vc_ctrl_req->input;
>  	input->status = cpu_to_le32(VIRTIO_CRYPTO_ERR);
>  
> -- 
> 2.34.1
>