devpts: correctly set default options
devpts_get_sb() calls memset(0) to clear mount options and calls
parse_mount_options() if user specified any mount options.
The memset(0) is bogus since the 'mode' and 'ptmxmode' options are
non-zero by default. parse_mount_options() restores options to default
anyway and can properly deal with NULL mount options.
So in devpts_get_sb() remove memset(0) and call parse_mount_options() even
for NULL mount options.
Bug reported by Eric Paris: http://lkml.org/lkml/2009/5/7/448.
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Reported-by: Eric Paris <eparis@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Reviewed-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 21165cf..c68edb9 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -90,6 +90,15 @@
#define PARSE_MOUNT 0
#define PARSE_REMOUNT 1
+/*
+ * parse_mount_options():
+ * Set @opts to mount options specified in @data. If an option is not
+ * specified in @data, set it to its default value. The exception is
+ * 'newinstance' option which can only be set/cleared on a mount (i.e.
+ * cannot be changed during remount).
+ *
+ * Note: @data may be NULL (in which case all options are set to default).
+ */
static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
{
char *p;
@@ -355,12 +364,9 @@
struct pts_mount_opts opts;
struct super_block *s;
- memset(&opts, 0, sizeof(opts));
- if (data) {
- error = parse_mount_options(data, PARSE_MOUNT, &opts);
- if (error)
- return error;
- }
+ error = parse_mount_options(data, PARSE_MOUNT, &opts);
+ if (error)
+ return error;
if (opts.newinstance)
s = sget(fs_type, NULL, set_anon_super, NULL);