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Bluetooth: Release rfcomm_dev only once

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No logic prevents an rfcomm_dev from being released multiple
times. For example, if the rfcomm_dev ref count is large due
to pending tx, then multiple RFCOMMRELEASEDEV ioctls may
mistakenly release the rfcomm_dev too many times. Note that
concurrent ioctls are not required to create this condition.

Introduce RFCOMM_DEV_RELEASED status bit which guarantees the
rfcomm_dev can only be released once.

NB: Since the flags are exported to userspace, introduce the status
field to track state for which userspace should not be aware.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Peter Hurley 2014-02-09 20:59:07 -05:00 committed by Marcel Holtmann
parent 960603a54a
commit 1c64834e06
2 changed files with 14 additions and 3 deletions
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6
include/net/bluetooth/rfcomm.h
View file

@ -324,11 +324,15 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel,
#define RFCOMMGETDEVINFO _IOR('R', 211, int)
#define RFCOMMSTEALDLC _IOW('R', 220, int)
/* rfcomm_dev.flags bit definitions */
#define RFCOMM_REUSE_DLC 0
#define RFCOMM_RELEASE_ONHUP 1
#define RFCOMM_HANGUP_NOW 2
#define RFCOMM_TTY_ATTACHED 3
#define RFCOMM_TTY_RELEASED 4
#define RFCOMM_DEFUNCT_BIT4 4 /* don't reuse this bit - userspace visible */
/* rfcomm_dev.status bit definitions */
#define RFCOMM_DEV_RELEASED 0
struct rfcomm_dev_req {
s16 dev_id;

11
net/bluetooth/rfcomm/tty.c
View file

@ -51,6 +51,8 @@ struct rfcomm_dev {
unsigned long flags;
int err;
unsigned long status; /* don't export to userspace */
bdaddr_t src;
bdaddr_t dst;
u8 channel;
@ -423,6 +425,12 @@ static int rfcomm_release_dev(void __user *arg)
return -EPERM;
}
/* only release once */
if (test_and_set_bit(RFCOMM_DEV_RELEASED, &dev->status)) {
tty_port_put(&dev->port);
return -EALREADY;
}
if (req.flags & (1 << RFCOMM_HANGUP_NOW))
rfcomm_dlc_close(dev->dlc, 0);
@ -433,8 +441,7 @@ static int rfcomm_release_dev(void __user *arg)
tty_kref_put(tty);
}
if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags) &&
!test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags))
if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags))
tty_port_put(&dev->port);
tty_port_put(&dev->port);