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    SubjectRe: [PATCH 06/14] Fix CFLAGS for UBSAN_BOUNDS on Clang
    On Tue, Sep 15, 2020 at 01:18:11PM +0200, Marco Elver wrote:
    > On Tue, 15 Sep 2020 at 12:25, George Popescu <georgepope@google.com> 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@google.com>
    > > > >
    > > > > 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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