On Tue, Sep 15, 2020 at 01:18:11PM +0200, Marco Elver wrote:

On Tue, 15 Sep 2020 at 12:25, George Popescu [off-list ref] wrote:

quoted

On Mon, Sep 14, 2020 at 03:13:14PM -0700, Kees Cook wrote:

quoted

On Mon, Sep 14, 2020 at 05:27:42PM +0000, George-Aurelian Popescu wrote:

quoted

From: George Popescu <redacted>

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.

Thanks,
George

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