crypto: scatterwalk - Fix test in scatterwalk_done

[ Upstream commit 5f070e81 ]

When there is more data to be processed, the current test in
scatterwalk_done may prevent us from calling pagedone even when
we should.

In particular, if we're on an SG entry spanning multiple pages
where the last page is not a full page, we will incorrectly skip
calling pagedone on the second last page.

This patch fixes this by adding a separate test for whether we've
reached the end of a page.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

crypto/scatterwalk.c

@@ -68,7 +68,8 @@ static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
 
 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
 {
-	if (!(scatterwalk_pagelen(walk) & (PAGE_SIZE - 1)) || !more)
+	if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
+	    !(walk->offset & (PAGE_SIZE - 1)))
 		scatterwalk_pagedone(walk, out, more);
 }
 EXPORT_SYMBOL_GPL(scatterwalk_done);