[ 039/108] ocfs2: fix NULL pointer dereference in __ocfs2_change_file_space()

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

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

From: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>

commit a4e08d001f2e50bb8b3c4eebadcf08e5535f02ee upstream.

As ocfs2_fallocate() will invoke __ocfs2_change_file_space() with a NULL
as the first parameter (file), it may trigger a NULL pointer dereferrence
due to a missing check.

Addresses http://bugs.launchpad.net/bugs/1006012

Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
Reported-by: Bret Towe <magnade@xxxxxxxxx>
Tested-by: Bret Towe <magnade@xxxxxxxxx>
Cc: Sunil Mushran <sunil.mushran@xxxxxxxxxx>
Acked-by: Joel Becker <jlbec@xxxxxxxxxxxx>
Acked-by: Mark Fasheh <mfasheh@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/ocfs2/file.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 98513c8..7602783 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1950,7 +1950,7 @@ static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
 	if (ret < 0)
 		mlog_errno(ret);
 
-	if (file->f_flags & O_SYNC)
+	if (file && (file->f_flags & O_SYNC))
 		handle->h_sync = 1;
 
 	ocfs2_commit_trans(osb, handle);


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