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SubjectRe: [PATCH 3/3] Fix insn.c misaligned address error
Em Wed, Jul 24, 2019 at 11:45:12AM -0700, Numfor Mbiziwo-Tiapo escreveu:
> The ubsan (undefined behavior sanitizer) version of perf throws an
> error on the 'x86 instruction decoder - new instructions' function
> of perf test.
>
> To reproduce this run:
> make -C tools/perf USE_CLANG=1 EXTRA_CFLAGS="-fsanitize=undefined"
>
> then run: tools/perf/perf test 62 -v
>
> The error occurs in the __get_next macro (line 34) where an int is
> read from a potentially unaligned address. Using memcpy instead of
> assignment from an unaligned pointer.

Since this came from the kernel, don't we have to fix it there as well?
Masami, Adrian?

[acme@quaco perf]$ find . -name insn.c
./arch/x86/lib/insn.c
./arch/arm/kernel/insn.c
./arch/arm64/kernel/insn.c
./tools/objtool/arch/x86/lib/insn.c
./tools/perf/util/intel-pt-decoder/insn.c
[acme@quaco perf]$ diff -u ./tools/perf/util/intel-pt-decoder/insn.c ./arch/x86/lib/insn.c
--- ./tools/perf/util/intel-pt-decoder/insn.c 2019-07-06 16:59:05.734265998 -0300
+++ ./arch/x86/lib/insn.c 2019-07-06 16:59:01.369202998 -0300
@@ -10,8 +10,8 @@
#else
#include <string.h>
#endif
-#include "inat.h"
-#include "insn.h"
+#include <asm/inat.h>
+#include <asm/insn.h>

/* Verify next sizeof(t) bytes can be on the same instruction */
#define validate_next(t, insn, n) \
[acme@quaco perf]$

- Arnaldo

> Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com>
> ---
> tools/perf/util/intel-pt-decoder/insn.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/intel-pt-decoder/insn.c b/tools/perf/util/intel-pt-decoder/insn.c
> index ca983e2bea8b..de1944c60aa9 100644
> --- a/tools/perf/util/intel-pt-decoder/insn.c
> +++ b/tools/perf/util/intel-pt-decoder/insn.c
> @@ -31,7 +31,8 @@
> ((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
>
> #define __get_next(t, insn) \
> - ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
> + ({ t r; memcpy(&r, insn->next_byte, sizeof(t)); \
> + insn->next_byte += sizeof(t); r; })
>
> #define __peek_nbyte_next(t, insn, n) \
> ({ t r = *(t*)((insn)->next_byte + n); r; })
> --
> 2.22.0.657.g960e92d24f-goog

--

- Arnaldo

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