ocfs2: fix NULL pointer dereference in __ocfs2_change_file_space()

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@canonical.com>
Reported-by: Bret Towe <magnade@gmail.com>
Tested-by: Bret Towe <magnade@gmail.com>
Cc: Sunil Mushran <sunil.mushran@oracle.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 98513c8..7602783 100644 (file)
--- 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);