linux-kernel - [PATCH 3.16 081/346] crypto: scatterwalk

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Message-ID: <lsq.1479082460.640660497@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Herbert Xu" <herbert@...dor.apana.org.au>
Subject: [PATCH 3.16 081/346] crypto: scatterwalk - Fix test in
 scatterwalk_done

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@...dor.apana.org.au>

commit 5f070e81bee35f1b7bd1477bb223a873ff657803 upstream.

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.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 crypto/scatterwalk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -68,7 +68,8 @@ static void scatterwalk_pagedone(struct
 
 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);