From: Eddie Hung eddie.hung@mediatek.com

commit 64e6bbfff52db4bf6785fab9cffab850b2de6870 upstream.

There is a use-after-free issue, if access udc_name in function gadget_dev_desc_UDC_store after another context free udc_name in function unregister_gadget.

Context 1: gadget_dev_desc_UDC_store()->unregister_gadget()-> free udc_name->set udc_name to NULL

Context 2: gadget_dev_desc_UDC_show()-> access udc_name

Call trace: dump_backtrace+0x0/0x340 show_stack+0x14/0x1c dump_stack+0xe4/0x134 print_address_description+0x78/0x478 __kasan_report+0x270/0x2ec kasan_report+0x10/0x18 __asan_report_load1_noabort+0x18/0x20 string+0xf4/0x138 vsnprintf+0x428/0x14d0 sprintf+0xe4/0x12c gadget_dev_desc_UDC_show+0x54/0x64 configfs_read_file+0x210/0x3a0 __vfs_read+0xf0/0x49c vfs_read+0x130/0x2b4 SyS_read+0x114/0x208 el0_svc_naked+0x34/0x38

Add mutex_lock to protect this kind of scenario.

Signed-off-by: Eddie Hung eddie.hung@mediatek.com Signed-off-by: Macpaul Lin macpaul.lin@mediatek.com Reviewed-by: Peter Chen peter.chen@nxp.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/1609239215-21819-1-git-send-email-macpaul.lin@medi... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [Reference: CVE-2021-39648] [iwamatsu: struct usb_gadget_driver does not have udc_name variable. Change struct gadget_info's udc_name.] Signed-off-by: Nobuhiro Iwamatsu (CIP) nobuhiro1.iwamatsu@toshiba.co.jp --- drivers/usb/gadget/configfs.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index 0ef3f4e452428c..6e1172450c7345 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -241,7 +241,16 @@ static ssize_t gadget_dev_desc_bcdUSB_store(struct config_item *item,

static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page) { - return sprintf(page, "%s\n", to_gadget_info(item)->udc_name ?: ""); + struct gadget_info *gi = to_gadget_info(item); + char *udc_name; + int ret; + + mutex_lock(&gi->lock); + udc_name = gi->udc_name; + ret = sprintf(page, "%s\n", udc_name ?: ""); + mutex_unlock(&gi->lock); + + return ret; }

static int unregister_gadget(struct gadget_info *gi)