On Tue, 15 Sep 2020 at 14:01, George Popescu <georgepope@xxxxxxxxxx> wrote: > > On Tue, Sep 15, 2020 at 01:18:11PM +0200, Marco Elver wrote: > > On Tue, 15 Sep 2020 at 12:25, George Popescu <georgepope@xxxxxxxxxx> wrote: > > > On Mon, Sep 14, 2020 at 03:13:14PM -0700, Kees Cook wrote: > > > > On Mon, Sep 14, 2020 at 05:27:42PM +0000, George-Aurelian Popescu wrote: > > > > > From: George Popescu <georgepope@xxxxxxxxxx> > > > > > > > > > > When the kernel is compiled with Clang, UBSAN_BOUNDS inserts a brk after > > > > > the handler call, preventing it from printing any information processed > > > > > inside the buffer. > > > > > For Clang -fsanitize=bounds expands to -fsanitize=array-bounds and > > > > > -fsanitize=local-bounds, and the latter adds a brk after the handler > > > > > call > > > > > > > This would mean losing the local-bounds coverage. I tried to test it without > > > local-bounds and with a locally defined array on the stack and it works fine > > > (the handler is called and the error reported). For me it feels like > > > --array-bounds and --local-bounds are triggered for the same type of > > > undefined_behaviours but they are handling them different. > > > > Does -fno-sanitize-trap=bounds help?> > > I tried replacing it with: > ifdef CONFIG_CC_IS_CLANG > CFLAGS_UBSAN += $(call cc-option, -fno-sanitize-trap=bounds) > CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds) > else > CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds) > endif > > The code traps. What's your config? Do you have CONFIG_UBSAN_TRAP=y? If so, you have 2 options: honor UBSAN_TRAP and crash the kernel, or have a 'CFLAGS_REMOVE_... = -fsanitize-undefined-trap-on-error' for the files where you can't deal with traps. Thanks, -- Marco
