[PATCH v2 03/29] crypto: skcipher - remove redundant clamping to page size

Eric Biggers
2024-12-30T00:16:00Z

In the case where skcipher_walk_next() allocates a bounce page, that
page by definition has size PAGE_SIZE. The number of bytes to copy 'n'
is guaranteed to fit in it, since earlier in the function it was clamped
to be at most a page. Therefore remove the unnecessary logic that tried
to clamp 'n' again to fit in the bounce page.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
crypto/skcipher.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 887cbce8f78d..c627e267b125 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -248,28 +248,24 @@ static int skcipher_walk_next(struct skcipher_walk *walk)
return skcipher_walk_done(walk, -EINVAL);

slow_path:
return skcipher_next_slow(walk, bsize);
}
+ walk->nbytes = n;

if (unlikely((walk->in.offset | walk->out.offset) & walk->alignmask)) {
if (!walk->page) {
gfp_t gfp = skcipher_walk_gfp(walk);

walk->page = (void *)__get_free_page(gfp);
if (!walk->page)
goto slow_path;
}
-
- walk->nbytes = min_t(unsigned, n,
- PAGE_SIZE - offset_in_page(walk->page));
walk->flags |= SKCIPHER_WALK_COPY;
return skcipher_next_copy(walk);
}

- walk->nbytes = n;
-
return skcipher_next_fast(walk);
}

static int skcipher_copy_iv(struct skcipher_walk *walk)
{
--
2.47.1