From: Johan Hovold johan@kernel.org
commit a89936cce87d60766a75732a9e7e25c51164f47c upstream.
The tty driver name is used also after registering the driver and must specifically not be allocated on the stack to avoid leaking information to user space (or triggering an oops).
Drivers should not try to encode topology information in the tty device name but this one snuck in through staging without anyone noticing and another driver has since copied this malpractice.
Fixing the ABI is a separate issue, but this at least plugs the security hole.
Fixes: ba4dc61fe8c5 ("Staging: ipack: add support for IP-OCTAL mezzanine board") Cc: stable@vger.kernel.org # 3.5 Acked-by: Samuel Iglesias Gonsalvez siglesias@igalia.com Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20210917114622.5412-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/ipack/devices/ipoctal.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
--- a/drivers/ipack/devices/ipoctal.c +++ b/drivers/ipack/devices/ipoctal.c @@ -269,7 +269,6 @@ static int ipoctal_inst_slot(struct ipoc int res; int i; struct tty_driver *tty; - char name[20]; struct ipoctal_channel *channel; struct ipack_region *region; void __iomem *addr; @@ -360,8 +359,11 @@ static int ipoctal_inst_slot(struct ipoc /* Fill struct tty_driver with ipoctal data */ tty->owner = THIS_MODULE; tty->driver_name = KBUILD_MODNAME; - sprintf(name, KBUILD_MODNAME ".%d.%d.", bus_nr, slot); - tty->name = name; + tty->name = kasprintf(GFP_KERNEL, KBUILD_MODNAME ".%d.%d.", bus_nr, slot); + if (!tty->name) { + res = -ENOMEM; + goto err_put_driver; + } tty->major = 0;
tty->minor_start = 0; @@ -377,8 +379,7 @@ static int ipoctal_inst_slot(struct ipoc res = tty_register_driver(tty); if (res) { dev_err(&ipoctal->dev->dev, "Can't register tty driver.\n"); - put_tty_driver(tty); - return res; + goto err_free_name; }
/* Save struct tty_driver for use it when uninstalling the device */ @@ -415,6 +416,13 @@ static int ipoctal_inst_slot(struct ipoc ipoctal_irq_handler, ipoctal);
return 0; + +err_free_name: + kfree(tty->name); +err_put_driver: + put_tty_driver(tty); + + return res; }
static inline int ipoctal_copy_write_buffer(struct ipoctal_channel *channel, @@ -704,6 +712,7 @@ static void __ipoctal_remove(struct ipoc }
tty_unregister_driver(ipoctal->tty_drv); + kfree(ipoctal->tty_drv->name); put_tty_driver(ipoctal->tty_drv); kfree(ipoctal); }