From: Eddie Hung <eddie.hung@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx> Reviewed-by: Peter Chen <peter.chen@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/1609239215-21819-1-git-send-email-macpaul.lin@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/configfs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -232,9 +232,16 @@ static ssize_t gadget_dev_desc_bcdUSB_st static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page) { - char *udc_name = to_gadget_info(item)->composite.gadget_driver.udc_name; + struct gadget_info *gi = to_gadget_info(item); + char *udc_name; + int ret; - return sprintf(page, "%s\n", udc_name ?: ""); + mutex_lock(&gi->lock); + udc_name = gi->composite.gadget_driver.udc_name; + ret = sprintf(page, "%s\n", udc_name ?: ""); + mutex_unlock(&gi->lock); + + return ret; } static int unregister_gadget(struct gadget_info *gi)
