diff options
| author | Sascha Hauer <s.hauer@pengutronix.de> | 2022-11-04 14:10:31 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-09 12:39:33 +0100 |
| commit | d65e6b6e884a38360fc1cadf8ff31858151da57f (patch) | |
| tree | 63ce0e19adc32e33bf5002bd26ecf8b536f8d255 /drivers/usb/gadget | |
| parent | 321b59870f850a10dbb211ecd2bd87b41497ea6f (diff) | |
| download | linux-d65e6b6e884a38360fc1cadf8ff31858151da57f.tar.bz2 | |
usb: gadget: f_ecm: Always set current gadget in ecm_bind()
The gadget may change over bind/unbind cycles, so set it each time during
bind, not only the first time. Without it we get a use-after-free with
the following example:
cd /sys/kernel/config/usb_gadget/; mkdir -p mygadget; cd mygadget
mkdir -p configs/c.1/strings/0x409
echo "C1:Composite Device" > configs/c.1/strings/0x409/configuration
mkdir -p functions/ecm.usb0
ln -s functions/ecm.usb0 configs/c.1/
rmmod dummy_hcd
modprobe dummy_hcd
KASAN will complain shortly after the 'modprobe':
usb 2-1: New USB device found, idVendor=0000, idProduct=0000, bcdDevice= 6.01
usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
==================================================================
BUG: KASAN: use-after-free in gether_connect+0xb8/0x30c
Read of size 4 at addr cbef170c by task swapper/3/0
CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.1.0-rc3-00014-g41ff012f50cb-dirty #322
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x58/0x70
dump_stack_lvl from print_report+0x134/0x4d4
print_report from kasan_report+0x78/0x10c
kasan_report from gether_connect+0xb8/0x30c
gether_connect from ecm_set_alt+0x124/0x254
ecm_set_alt from composite_setup+0xb98/0x2b18
composite_setup from configfs_composite_setup+0x80/0x98
configfs_composite_setup from dummy_timer+0x8f0/0x14a0 [dummy_hcd]
...
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20221104131031.850850-3-s.hauer@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/gadget')
| -rw-r--r-- | drivers/usb/gadget/function/f_ecm.c | 22 |
1 files changed, 9 insertions, 13 deletions
diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c index ffe2486fce71..a7ab30e603e2 100644 --- a/drivers/usb/gadget/function/f_ecm.c +++ b/drivers/usb/gadget/function/f_ecm.c @@ -685,7 +685,7 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) struct usb_composite_dev *cdev = c->cdev; struct f_ecm *ecm = func_to_ecm(f); struct usb_string *us; - int status; + int status = 0; struct usb_ep *ep; struct f_ecm_opts *ecm_opts; @@ -695,23 +695,19 @@ ecm_bind(struct usb_configuration *c, struct usb_function *f) ecm_opts = container_of(f->fi, struct f_ecm_opts, func_inst); - /* - * in drivers/usb/gadget/configfs.c:configfs_composite_bind() - * configurations are bound in sequence with list_for_each_entry, - * in each configuration its functions are bound in sequence - * with list_for_each_entry, so we assume no race condition - * with regard to ecm_opts->bound access - */ + mutex_lock(&ecm_opts->lock); + + gether_set_gadget(ecm_opts->net, cdev->gadget); + if (!ecm_opts->bound) { - mutex_lock(&ecm_opts->lock); - gether_set_gadget(ecm_opts->net, cdev->gadget); status = gether_register_netdev(ecm_opts->net); - mutex_unlock(&ecm_opts->lock); - if (status) - return status; ecm_opts->bound = true; } + mutex_unlock(&ecm_opts->lock); + if (status) + return status; + ecm_string_defs[1].s = ecm->ethaddr; us = usb_gstrings_attach(cdev, ecm_strings, |