From 46f4e1b7d5fa3ddf2486bf69716c404147e38ebf Mon Sep 17 00:00:00 2001 From: Peter Osterlund Date: Fri, 20 May 2005 13:59:06 -0700 Subject: [PATCH] [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 Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/pktcdvd.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c index b9a6b7ad64f..bc56770bcc9 100644 --- a/drivers/block/pktcdvd.c +++ b/drivers/block/pktcdvd.c @@ -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; -- 2.20.1