crypto: rsa-pkcs1pad - don't allocate buffer on stack

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 <andrew.zaborowski@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index accc67d16686f9aee0b490ddcd9f3bbc4c990afc..50f5c97e10873cb727654ee68e10be536f75bed8 100644 (file)
--- 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(&miter, 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(&miter);
+
+                               chunk_len = min(miter.length, pad_left);
+                               memset(miter.addr, 0, chunk_len);
+                               pad_left -= chunk_len;
+                       }
+
+                       sg_miter_stop(&miter);
                }
 
                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;