Re: [PATCH] crypto: rsa-padding - don't allocate buffer on stack

[Herbert Xu]

Andrew Zaborowski  wrote:
> Avoid the s390 compile "warning: 'pkcs1pad_encrypt_sign_complete'
> uses dynamic stack allocation" reported by kbuild test robot.  Don't
> use a flat zero-filled buffer, instead zero the contents of the SGL.
> 
> Signed-off-by: Andrew Zaborowski 

Patch applied.  Thanks.
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[PATCH] crypto: rsa-padding - don't allocate buffer on stack

[Andrew Zaborowski]

Avoid the s390 compile "warning: 'pkcs1pad_encrypt_sign_complete'
uses dynamic stack allocation" reported by kbuild test robot.  Don't
use a flat zero-filled buffer, instead zero the contents of the SGL.

Signed-off-by: Andrew Zaborowski 
---
 crypto/rsa-pkcs1pad.c | 27 +++
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index accc67d..50f5c97 100644
--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -110,21 +110,32 @@ static int pkcs1pad_encrypt_sign_complete(struct 
akcipher_request *req, int err)
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
-   uint8_t zeros[ctx->key_size - req_ctx->child_req.dst_len];
+   size_t pad_len = ctx->key_size - req_ctx->child_req.dst_len;
+   size_t chunk_len, pad_left;
+   struct sg_mapping_iter miter;
 
if (!err) {
-   if (req_ctx->child_req.dst_len < ctx->key_size) {
-   memset(zeros, 0, sizeof(zeros));
-   sg_copy_from_buffer(req->dst,
-   sg_nents_for_len(req->dst,
-   sizeof(zeros)),
-   zeros, sizeof(zeros));
+   if (pad_len) {
+   sg_miter_start(, req->dst,
+   sg_nents_for_len(req->dst, pad_len),
+   SG_MITER_ATOMIC | SG_MITER_TO_SG);
+
+   pad_left = pad_len;
+   while (pad_left) {
+   sg_miter_next();
+
+   chunk_len = min(miter.length, pad_left);
+   memset(miter.addr, 0, chunk_len);
+   pad_left -= chunk_len;
+   }
+
+   sg_miter_stop();
}
 
sg_pcopy_from_buffer(req->dst,
sg_nents_for_len(req->dst, ctx->key_size),
req_ctx->out_buf, req_ctx->child_req.dst_len,
-   sizeof(zeros));
+   pad_len);
}
req->dst_len = ctx->key_size;
 
-- 
2.1.4

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