| Message ID | 20210907082318.7757-1-johan@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 91fac0741d4817945c6ee0a17591421e7f5ecb86 |
| Headers | show |
| Series | [v2] USB: cdc-acm: fix minor-number release | expand |
On 07.09.21 10:23, Johan Hovold wrote: > If the driver runs out of minor numbers it would release minor 0 and > allow another device to claim the minor while still in use. > > Fortunately, registering the tty class device of the second device would > fail (with a stack dump) due to the sysfs name collision so no memory is > leaked. > > Fixes: cae2bc768d17 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail") > Cc: stable@vger.kernel.org # 4.19 > Cc: Jaejoong Kim <climbbb.kim@gmail.com> > Signed-off-by: Johan Hovold <johan@kernel.org> Acked-by: Oliver Neukum <oneukum@suse.com>
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 4895325b16a4..5b90d0979c60 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -726,7 +726,8 @@ static void acm_port_destruct(struct tty_port *port) { struct acm *acm = container_of(port, struct acm, port); - acm_release_minor(acm); + if (acm->minor != ACM_MINOR_INVALID) + acm_release_minor(acm); usb_put_intf(acm->control); kfree(acm->country_codes); kfree(acm); @@ -1323,8 +1324,10 @@ static int acm_probe(struct usb_interface *intf, usb_get_intf(acm->control); /* undone in destruct() */ minor = acm_alloc_minor(acm); - if (minor < 0) + if (minor < 0) { + acm->minor = ACM_MINOR_INVALID; goto err_put_port; + } acm->minor = minor; acm->dev = usb_dev; diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index 8aef5eb769a0..3aa7f0a3ad71 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -22,6 +22,8 @@ #define ACM_TTY_MAJOR 166 #define ACM_TTY_MINORS 256 +#define ACM_MINOR_INVALID ACM_TTY_MINORS + /* * Requests. */
If the driver runs out of minor numbers it would release minor 0 and allow another device to claim the minor while still in use. Fortunately, registering the tty class device of the second device would fail (with a stack dump) due to the sysfs name collision so no memory is leaked. Fixes: cae2bc768d17 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail") Cc: stable@vger.kernel.org # 4.19 Cc: Jaejoong Kim <climbbb.kim@gmail.com> Signed-off-by: Johan Hovold <johan@kernel.org> --- Changes in v2 - add a dedicated define for the invalid minor number (Oliver) drivers/usb/class/cdc-acm.c | 7 +++++-- drivers/usb/class/cdc-acm.h | 2 ++ 2 files changed, 7 insertions(+), 2 deletions(-)