Commit 46f4e1b7 authored May 20, 2005 by Peter Osterlund Committed by Linus Torvalds May 20, 2005

[PATCH] packet driver permission checking fix



If you tried to open a packet device first in read-only mode and then a
second time in read-write mode, the second open succeeded even though the
device was not correctly set up for writing.  If you then tried to write
data to the device, the writes would fail with I/O errors.

This patch prevents that problem by making the second open fail with
-EBUSY.

Signed-off-by: Peter Osterlund <petero2@telia.com>
Cc: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 1c7878f0

drivers/block/pktcdvd.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -2021,7 +2021,13 @@ static int pkt_open(struct inode inode, struct file file)
		BUG_ON(pd->refcnt < 0);

		pd->refcnt++;
		if (pd->refcnt == 1) {
		if (pd->refcnt > 1) {
		if ((file->f_mode & FMODE_WRITE) &&
		!test_bit(PACKET_WRITABLE, &pd->flags)) {
		ret = -EBUSY;
		goto out_dec;
		}
		} else {
		if (pkt_open_dev(pd, file->f_mode & FMODE_WRITE)) {
		ret = -EIO;
		goto out_dec;

Admin message