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| author | William A. Kennington III <wak@google.com> | 2019-04-08 20:27:26 -0700 |
|---|---|---|
| committer | William A. Kennington III <wak@google.com> | 2019-04-11 18:40:25 -0700 |
| commit | 0d49e47978d5f2d0b108b0ddc65943763e88f729 (patch) | |
| tree | 73aaa9c1141a2e7425e92cb0ff660e0afcf7331e /include/ipmid | |
| parent | 11df4f6906edc0dfb23089a6e297158549c19ebd (diff) | |
| download | phosphor-host-ipmid-0d49e47978d5f2d0b108b0ddc65943763e88f729.tar.gz phosphor-host-ipmid-0d49e47978d5f2d0b108b0ddc65943763e88f729.zip | |
message/unpack: Fix undefined behavior
It's UB to shift an integer by the size of that integer. More
specifically, if you disable compiler optimization and try and unpack a
32 bit bitset you will end up with a 0x0 mask. Avoid UB by replacing
shift subtract with a negate shift.
Tested:
Unit tests pass now.
Change-Id: I03a6f866a51c955b57787d641da9180841747e4c
Signed-off-by: William A. Kennington III <wak@google.com>
Diffstat (limited to 'include/ipmid')
| -rw-r--r-- | include/ipmid/message/unpack.hpp | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/ipmid/message/unpack.hpp b/include/ipmid/message/unpack.hpp index d96928f..94f80f1 100644 --- a/include/ipmid/message/unpack.hpp +++ b/include/ipmid/message/unpack.hpp @@ -207,7 +207,9 @@ struct UnpackSingle<std::bitset<N>> { return -1; } - fixed_uint_t<details::bitStreamSize> bitmask = ((1 << count) - 1); + fixed_uint_t<details::bitStreamSize> bitmask = + ~fixed_uint_t<details::bitStreamSize>(0) >> + (details::bitStreamSize - count); t |= (p.bitStream & bitmask).convert_to<unsigned long long>(); p.bitStream >>= count; p.bitCount -= count; |
