diff mbox

[13/16] crypto: scatterwalk - Check for same address in map_and_copy

Message ID E1YvKdM-0005gB-AG@gondolin.me.apana.org.au (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show

Commit Message

Herbert Xu May 21, 2015, 7:11 a.m. UTC 
This patch adds a check for in scatterwalk_map_and_copy to avoid
copying from the same address to the same address.  This is going
to be used for IV copying in AEAD IV generators.

There is no provision for partial overlaps.

This patch also uses the new scatterwalk_ffwd instead of doing
it by hand in scatterwalk_map_and_copy.

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

 crypto/scatterwalk.c |   16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

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diff mbox

Patch

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index db920b5..8690324 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -104,22 +104,18 @@  void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 			      unsigned int start, unsigned int nbytes, int out)
 {
 	struct scatter_walk walk;
-	unsigned int offset = 0;
+	struct scatterlist tmp[2];
 
 	if (!nbytes)
 		return;
 
-	for (;;) {
-		scatterwalk_start(&walk, sg);
-
-		if (start < offset + sg->length)
-			break;
+	sg = scatterwalk_ffwd(tmp, sg, start);
 
-		offset += sg->length;
-		sg = sg_next(sg);
-	}
+	if (sg_page(sg) == virt_to_page(buf) &&
+	    sg->offset == offset_in_page(buf))
+		return;
 
-	scatterwalk_advance(&walk, start - offset);
+	scatterwalk_start(&walk, sg);
 	scatterwalk_copychunks(buf, &walk, nbytes, out);
 	scatterwalk_done(&walk, out, 0);
 }