On Mon, Apr 08, 2024 at 08:26:00PM +0200, Arnd Bergmann wrote: > On Thu, Mar 28, 2024, at 16:00, Dan Carpenter wrote: > > On Thu, Mar 28, 2024 at 03:04:54PM +0100, Arnd Bergmann wrote: > >> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > >> --- > >> This is from randconfig testing with random gcc versions, a .config to > >> reproduce is at https://pastebin.com/r13yezkU > >> --- > >> drivers/staging/greybus/fw-management.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c > >> index 3054f084d777..35bfdd5f32d2 100644 > >> --- a/drivers/staging/greybus/fw-management.c > >> +++ b/drivers/staging/greybus/fw-management.c > >> @@ -303,13 +303,13 @@ static int fw_mgmt_backend_fw_update_operation(struct fw_mgmt *fw_mgmt, > >> struct gb_fw_mgmt_backend_fw_update_request request; > >> int ret; > >> > >> - strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE); > >> + ret = strscpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE); > > > > This needs to be strscpy_pad() or it risks an information leak. > > Right, I think I misread the code thinking that the strncpy() > destination was user provided, but I see now that this copy is > from user-provided data into the stack, so the padding is indeed > stale stack data. > > I could not find out whether this gets copied back to userspace, > but adding the padding is safer indeed. > Grey bus is a bus, I'm not sure what's on the other end of the bus but I think we've generally said that the data needs to be zeroed... Although if that is true, why didn't I make this a Smatch warning? regards, dan carpenter
