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crypto: scatterwalk - Check for same address in map_and_copy

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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>
This commit is contained in:
Herbert Xu 2015-05-21 15:11:12 +08:00
parent 17db854699
commit 74412fd5d7
1 changed files with 6 additions and 10 deletions
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16
crypto/scatterwalk.c
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@ -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);
sg = scatterwalk_ffwd(tmp, sg, start);
if (start < offset + sg->length)
break;
if (sg_page(sg) == virt_to_page(buf) &&
sg->offset == offset_in_page(buf))
return;
offset += sg->length;
sg = sg_next(sg);
}
scatterwalk_advance(&walk, start - offset);
scatterwalk_start(&walk, sg);
scatterwalk_copychunks(buf, &walk, nbytes, out);
scatterwalk_done(&walk, out, 0);
}