From: Johan Hovold johan@kernel.org

stable inclusion from stable-5.10.71 commit 5f6a309a699675680df15d9b6d389114515b4426 bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4NI CVE: CVE-2021-47401

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

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 Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com --- drivers/ipack/devices/ipoctal.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/ipack/devices/ipoctal.c b/drivers/ipack/devices/ipoctal.c index 75dd15d66df6..aeadeaafdb26 100644 --- a/drivers/ipack/devices/ipoctal.c +++ b/drivers/ipack/devices/ipoctal.c @@ -269,7 +269,6 @@ static int ipoctal_inst_slot(struct ipoctal *ipoctal, unsigned int bus_nr, 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 ipoctal *ipoctal, unsigned int bus_nr, /* 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 ipoctal *ipoctal, unsigned int bus_nr, 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 ipoctal *ipoctal, unsigned int bus_nr, 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, @@ -703,6 +711,7 @@ static void __ipoctal_remove(struct ipoctal *ipoctal) }

tty_unregister_driver(ipoctal->tty_drv); + kfree(ipoctal->tty_drv->name); put_tty_driver(ipoctal->tty_drv); kfree(ipoctal); }