On Mon, Dec 27, 2021 at 01:47:35PM +0100, Greg KH wrote: > On Thu, Dec 23, 2021 at 02:26:26PM +0900, Nobuhiro Iwamatsu wrote: > > 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> > > [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@xxxxxxxxxxxxx> > > --- > > drivers/usb/gadget/configfs.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > Now queued up, thanks. > > greg k-h Oops, nope, this gives me a build warning, something is wrong with this change: CC [M] drivers/usb/gadget/configfs.o drivers/usb/gadget/configfs.c: In function ‘gadget_dev_desc_UDC_show’: drivers/usb/gadget/configfs.c:249:18: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] 249 | udc_name = gi->udc_name; | ^ Please always test-build your patches :( thanks, greg k-h
