From: "[email protected]" <[email protected]> The patch fixes a problem in the lp driver that can cause oopses as follows: process A: calls lp_write, which in turn calls parport_ieee1284_write_compat, and that invokes parport_wait_peripheral process B: meanwhile does an ioctl(LPGETSTATUS), which call lp_release_parport when done. This function will set physport->cad = NULL. process A: parport_wait_peripheral tries to dereference physport->cad and dies
So, protect that code with the port_mutex in order to protect against simultaneous calls to lp_read/lp_write. Similar protection is probably required for ioctl(LPRESET)... This patch was done by IBM a while back and we (at suse) have that since at least 2004 in our repos. Let's make it upstream. Signed-off-by: [email protected] Signed-off-by: Jiri Slaby <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> --- drivers/char/lp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/char/lp.c b/drivers/char/lp.c index dafd9ac..0913d79 100644 --- a/drivers/char/lp.c +++ b/drivers/char/lp.c @@ -622,9 +622,12 @@ static int lp_do_ioctl(unsigned int minor, unsigned int cmd, return -EFAULT; break; case LPGETSTATUS: + if (mutex_lock_interruptible(&lp_table[minor].port_mutex)) + return -EINTR; lp_claim_parport_or_block (&lp_table[minor]); status = r_str(minor); lp_release_parport (&lp_table[minor]); + mutex_unlock(&lp_table[minor].port_mutex); if (copy_to_user(argp, &status, sizeof(int))) return -EFAULT; -- 1.8.2.1 -- 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/
