On Tuesday, July 26, 2016 8:21:37 AM CEST Kees Cook wrote: > On Tue, Jul 26, 2016 at 5:28 AM, Arnd Bergmann <a...@arndb.de> wrote: > > The do_usercopy_stack() function uses uninitialized stack data to initialize > > more of the stack, which causes a warning in some configurations (ARM > > allmodconfig): > > > > drivers/misc/lkdtm_usercopy.c:52:15: warning: 'bad_stack' may be used > > uninitialized in this function [-Wmaybe-uninitialized] > > > > The warning gets reports by Mark Brown's build bot and looks correct (we > > are trying > > to trick the compiler here, and sometimes the compiler notices), and I > > could reproduce > > it with gcc-4.7 through gcc-5.3 but not gcc-6.1 for some reason. > > > > This changes the code to use the low byte of the address of the stack to > > initialize > > the stack data, instead of using data from the stack itself, to avoid the > > warning. > > > > Signed-off-by: Arnd Bergmann <a...@arndb.de> > > Fixes: a3dff71c1c88 ("lkdtm: split usercopy tests to separate file") > > Acked-by: Kees Cook <keesc...@chromium.org> > > I thought I already sent this fix to Greg?
Possible. I mentioned the problem to you when it first showed up, but noticed today that I didn't have a patch for it in my testing tree (since I test with gcc-6.1, which doesn't show the bug). > Maybe it got lost... More likely that it's still in his backlog then. Arnd