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authorPeter Osterlund <petero2@telia.com>2005-05-20 13:59:06 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-05-20 15:48:16 -0700
commit46f4e1b7d5fa3ddf2486bf69716c404147e38ebf (patch)
tree8c632478e9e5c0b0a2f9601542e54d8f02250cb1
parent1c7878f024705594ac455e501ad51e475a400d5d (diff)
[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>
-rw-r--r--drivers/block/pktcdvd.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index b9a6b7ad64f3..bc56770bcc90 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;