crypto: adiantum - flush destination page before unmapping

Upon additional review, the new fast path in adiantum_finish() is
missing the call to flush_dcache_page() that scatterwalk_map_and_copy()
was doing.  It's apparently debatable whether flush_dcache_page() is
actually needed, as per the discussion at
https://lore.kernel.org/lkml/YYP1lAq46NWzhOf0@casper.infradead.org/T/#u.
However, it appears that currently all the helper functions that write
to a page, such as scatterwalk_map_and_copy(), memcpy_to_page(), and
memzero_page(), do the dcache flush.  So do it to be consistent.

Fixes: dadf5e56c967 ("crypto: adiantum - add fast path for single-page messages")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/adiantum.c b/crypto/adiantum.c
index 9ff3376f9ed35f609f86eb2c92fcd25c1854b435..60f3883b736aa823e7106fcb90baa853c79d5a26 100644 (file)
--- a/crypto/adiantum.c
+++ b/crypto/adiantum.c
@@ -300,7 +300,8 @@ static int adiantum_finish(struct skcipher_request *req)
        le128_sub(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &rctx->header_hash);
        if (dst_nents == 1 && dst->offset + req->cryptlen <= PAGE_SIZE) {
                /* Fast path for single-page destination */
-               void *virt = kmap_local_page(sg_page(dst)) + dst->offset;
+               struct page *page = sg_page(dst);
+               void *virt = kmap_local_page(page) + dst->offset;
 
                err = crypto_shash_digest(&rctx->u.hash_desc, virt, bulk_len,
                                          (u8 *)&digest);
@@ -310,6 +311,7 @@ static int adiantum_finish(struct skcipher_request *req)
                }
                le128_sub(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &digest);
                memcpy(virt + bulk_len, &rctx->rbuf.bignum, sizeof(le128));
+               flush_dcache_page(page);
                kunmap_local(virt);
        } else {
                /* Slow path that works for any destination scatterlist */