kcov: update pos before writing pc in trace function

In __sanitizer_cov_trace_pc(), previously we write pc before updating pos.
However, some early interrupt code could bypass check_kcov_mode() check
and invoke __sanitizer_cov_trace_pc().  If such interrupt is raised
between writing pc and updating pos, the pc could be overitten by the
recursive __sanitizer_cov_trace_pc().

As suggested by Dmitry, we cold update pos before writing pc to avoid such
interleaving.

Apply the same change to write_comp_data().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Congyu Liu <[email protected]>
Reviewed-by: Dmitry Vyukov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions