On Mon, Jun 17, 2019 at 03:25:17PM +0200, Arnd Bergmann wrote:
> After the latest addition, the stack usage of sun4i_ss_cipher_poll
> grew beyond the warning limit when KASAN is enabled:
>
> drivers/crypto/sunxi-ss/sun4i-ss-cipher.c:118:12: error: stack frame size of 1152 bytes in function 'sun4i_ss_cipher_poll' [-Werror,-Wframe-larger-than=]
> static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
>
> Reduce it in three ways:
>
> - split out the new code into a separate function so its stack
> usage can overlap that of the sun4i_ss_opti_poll() code path
> - mark both special cases as noinline_for_stack, which should
> ideally result in a tail call that frees the rest of the
> stack
> - move the buf and obuf variables into the code blocks in
> which they are used.
>
> The three separate functions now use 144, 640 and 304 bytes of kernel
> stack, respectively.
>
> Fixes: 0ae1f46c55f8 ("crypto: sun4i-ss - fallback when length is not multiple of blocksize")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/crypto/sunxi-ss/sun4i-ss-cipher.c | 47 +++++++++++++++--------
> 1 file changed, 30 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> index 7b0c42882830..4ab14d58e85b 100644
> --- a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> +++ b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> @@ -12,7 +12,7 @@
> */
> #include "sun4i-ss.h"
>
> -static int sun4i_ss_opti_poll(struct skcipher_request *areq)
> +static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
> {
> struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
> struct sun4i_tfm_ctx *op = crypto_skcipher_ctx(tfm);
> @@ -114,6 +114,29 @@ static int sun4i_ss_opti_poll(struct skcipher_request *areq)
> return err;
> }
>
> +
> +static int noinline_for_stack sun4i_ss_cipher_poll_fallback(struct skcipher_request *areq)
> +{
> + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(areq);
> + struct sun4i_tfm_ctx *op = crypto_skcipher_ctx(tfm);
> + struct sun4i_cipher_req_ctx *ctx = skcipher_request_ctx(areq);
> + SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, op->fallback_tfm);
> + int err;
> +
> + skcipher_request_set_sync_tfm(subreq, op->fallback_tfm);
> + skcipher_request_set_callback(subreq, areq->base.flags, NULL,
> + NULL);
> + skcipher_request_set_crypt(subreq, areq->src, areq->dst,
> + areq->cryptlen, areq->iv);
> + if (ctx->mode & SS_DECRYPTION)
> + err = crypto_skcipher_decrypt(subreq);
> + else
> + err = crypto_skcipher_encrypt(subreq);
> + skcipher_request_zero(subreq);
> +
> + return err;
> +}
> +
> /* Generic function that support SG with size not multiple of 4 */
> static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
> {
> @@ -140,8 +163,6 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
> unsigned int todo;
> struct sg_mapping_iter mi, mo;
> unsigned int oi, oo; /* offset for in and out */
> - char buf[4 * SS_RX_MAX];/* buffer for linearize SG src */
> - char bufo[4 * SS_TX_MAX]; /* buffer for linearize SG dst */
> unsigned int ob = 0; /* offset in buf */
> unsigned int obo = 0; /* offset in bufo*/
> unsigned int obl = 0; /* length of data in bufo */
> @@ -178,20 +199,8 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
> if (no_chunk == 1 && !need_fallback)
> return sun4i_ss_opti_poll(areq);
>
> - if (need_fallback) {
> - SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, op->fallback_tfm);
> - skcipher_request_set_sync_tfm(subreq, op->fallback_tfm);
> - skcipher_request_set_callback(subreq, areq->base.flags, NULL,
> - NULL);
> - skcipher_request_set_crypt(subreq, areq->src, areq->dst,
> - areq->cryptlen, areq->iv);
> - if (ctx->mode & SS_DECRYPTION)
> - err = crypto_skcipher_decrypt(subreq);
> - else
> - err = crypto_skcipher_encrypt(subreq);
> - skcipher_request_zero(subreq);
> - return err;
> - }
> + if (need_fallback)
> + return sun4i_ss_cipher_poll_fallback(areq);
>
> spin_lock_irqsave(&ss->slock, flags);
>
> @@ -224,6 +233,8 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
>
> while (oleft) {
> if (ileft) {
> + char buf[4 * SS_RX_MAX];/* buffer for linearize SG src */
> +
> /*
> * todo is the number of consecutive 4byte word that we
> * can read from current SG
> @@ -281,6 +292,8 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
> oo = 0;
> }
> } else {
> + char bufo[4 * SS_TX_MAX]; /* buffer for linearize SG dst */
> +
> /*
> * read obl bytes in bufo, we read at maximum for
> * emptying the device
> --
> 2.20.0
>
Tested-by: Corentin LABBE <clabbe.montjoie@xxxxxxxxx>
