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 <[email protected]> --- include/net/bluetooth/rfcomm.h | 6 +++++- net/bluetooth/rfcomm/tty.c | 11 +++++++++-- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h index 486213a..29d9727 100644 --- a/include/net/bluetooth/rfcomm.h +++ b/include/net/bluetooth/rfcomm.h @@ -323,11 +323,15 @@ 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; diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c index b385d99..d9d4bc8 100644 --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -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); -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
