linux-kernel - [PATCH] FS-Cache: Remove unneeded null checks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20100601195822.8452.90732.stgit@warthog.procyon.org.uk>
Date:	Tue, 01 Jun 2010 20:58:22 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-cachefs@...hat.com, linux-kernel@...r.kernel.org,
	Dan Carpenter <error27@...il.com>,
	David Howells <dhowells@...hat.com>
Subject: [PATCH] FS-Cache: Remove unneeded null checks

From: Dan Carpenter <error27@...il.com>

fscache_write_op() makes unnecessary checks of the page variable to see if it
is NULL.  It can't be NULL at those points as the kernel would already have
crashed a little higher up where we examined page->index.

Furthermore, unless radix_tree_gang_lookup_tag() can return 1 but no page, a
NULL pointer crash should not be encountered there as we can only get there if
r_t_g_l_t() returned 1.

Signed-off-by: Dan Carpenter <error27@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/fscache/page.c |   36 ++++++++++++++++--------------------
 1 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 9461617..5b9b00a 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -710,30 +710,26 @@ static void fscache_write_op(struct fscache_operation *_op)
 		goto superseded;
 	}
 
-	if (page) {
-		radix_tree_tag_set(&cookie->stores, page->index,
-				   FSCACHE_COOKIE_STORING_TAG);
-		radix_tree_tag_clear(&cookie->stores, page->index,
-				     FSCACHE_COOKIE_PENDING_TAG);
-	}
+	radix_tree_tag_set(&cookie->stores, page->index,
+			   FSCACHE_COOKIE_STORING_TAG);
+	radix_tree_tag_clear(&cookie->stores, page->index,
+			     FSCACHE_COOKIE_PENDING_TAG);
 
 	spin_unlock(&cookie->stores_lock);
 	spin_unlock(&object->lock);
 
-	if (page) {
-		fscache_set_op_state(&op->op, "Store");
-		fscache_stat(&fscache_n_store_pages);
-		fscache_stat(&fscache_n_cop_write_page);
-		ret = object->cache->ops->write_page(op, page);
-		fscache_stat_d(&fscache_n_cop_write_page);
-		fscache_set_op_state(&op->op, "EndWrite");
-		fscache_end_page_write(object, page);
-		if (ret < 0) {
-			fscache_set_op_state(&op->op, "Abort");
-			fscache_abort_object(object);
-		} else {
-			fscache_enqueue_operation(&op->op);
-		}
+	fscache_set_op_state(&op->op, "Store");
+	fscache_stat(&fscache_n_store_pages);
+	fscache_stat(&fscache_n_cop_write_page);
+	ret = object->cache->ops->write_page(op, page);
+	fscache_stat_d(&fscache_n_cop_write_page);
+	fscache_set_op_state(&op->op, "EndWrite");
+	fscache_end_page_write(object, page);
+	if (ret < 0) {
+		fscache_set_op_state(&op->op, "Abort");
+		fscache_abort_object(object);
+	} else {
+		fscache_enqueue_operation(&op->op);
 	}
 
 	_leave("");

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/