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SubjectRE: [PATCH 3/3] Fix insn.c misaligned address error
Date
From: Numfor Mbiziwo-Tiapo
> Sent: 24 July 2019 19:45
>
> 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.
...
> #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; })

Isn't there a get_unaligned_u32() (or similar) that can be used?

David

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