linux-ext4 - Re: [ext4:dev 40/60] fs/ext4/inode.c:1953 __ext4_journalled_writepage() error: potential NULL dereference 'page

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Message-Id: <1354627545-2792-1-git-send-email-tm@tao.ma>
Date:	Tue,  4 Dec 2012 21:25:45 +0800
From:	Tao Ma <tm@....ma>
To:	dan.carpenter@...cle.com
Cc:	tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [ext4:dev 40/60] fs/ext4/inode.c:1953 __ext4_journalled_writepage() error: potential NULL dereference 'page_bufs'.

Hi Dan,
	Thanks for the report. Can you check whether this patch
works for you?

Thanks
Tao

From: Tao Ma <boyu.mt@...bao.com>
Subject: [PATCH] ext4: Fix a build warning in __ext4_journalled_writepage.

smatch complains:
fs/ext4/inode.c:1953 __ext4_journalled_writepage() error: potential NULL dereference 'page_bufs'.

So add the check for it.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Tao Ma <boyu.mt@...bao.com>
---
 fs/ext4/inode.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index dbc5784..431201b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1956,7 +1956,7 @@ static int __ext4_journalled_writepage(struct page *page,
 	struct buffer_head *page_bufs = NULL;
 	handle_t *handle = NULL;
 	int ret = 0;
-	int err;
+	int err = 0;
 	struct buffer_head *inode_bh = NULL;

 	ClearPageChecked(page);
@@ -1987,8 +1987,7 @@ static int __ext4_journalled_writepage(struct page *page,
 		ret = ext4_journal_get_write_access(handle, inode_bh);

 		err = ext4_handle_dirty_metadata(handle, inode, inode_bh);
-
-	} else {
+	} else if (page_bufs) {
 		ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
 					     do_journal_get_write_access);

-- 
1.7.1

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