[llvm] r217708 - llvm-profdata: Avoid undefined behaviour when reading raw profiles

[David Blaikie]

On Fri, Sep 12, 2014 at 2:22 PM, Justin Bogner <mail at justinbogner.com>
wrote:

> Author: bogner
> Date: Fri Sep 12 16:22:55 2014
> New Revision: 217708
>
> URL: http://llvm.org/viewvc/llvm-project?rev=217708&view=rev
> Log:
> llvm-profdata: Avoid undefined behaviour when reading raw profiles
>
> The raw profiles that are generated in compiler-rt always add padding
> so that each profile is aligned, so we can simply treat files that
> don't have this property as malformed.
>

Any chance of changing this to not rely on UB (this code looks like it's
violating C++ aliasing rules pretty consistently) and instead using memcpy?


>
> Caught by Alexey's new ubsan bot. Thanks!
>
> Modified:
>     llvm/trunk/lib/ProfileData/InstrProfReader.cpp
>     llvm/trunk/test/tools/llvm-profdata/raw-two-profiles.test
>
> Modified: llvm/trunk/lib/ProfileData/InstrProfReader.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ProfileData/InstrProfReader.cpp?rev=217708&r1=217707&r2=217708&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/ProfileData/InstrProfReader.cpp (original)
> +++ llvm/trunk/lib/ProfileData/InstrProfReader.cpp Fri Sep 12 16:22:55 2014
> @@ -190,6 +190,9 @@ RawInstrProfReader<IntPtrT>::readNextHea
>    // garbage at the end of the file.
>    if (CurrentPos + sizeof(RawHeader) > End)
>      return instrprof_error::malformed;
> +  // The writer ensures each profile is padded to start at an aligned
> address.
> +  if (reinterpret_cast<size_t>(CurrentPos) % alignOf<uint64_t>())
> +    return instrprof_error::malformed;
>    // The magic should have the same byte order as in the previous header.
>    uint64_t Magic = *reinterpret_cast<const uint64_t *>(CurrentPos);
>    if (Magic != swap(getRawMagic<IntPtrT>()))
>
> Modified: llvm/trunk/test/tools/llvm-profdata/raw-two-profiles.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-profdata/raw-two-profiles.test?rev=217708&r1=217707&r2=217708&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-profdata/raw-two-profiles.test (original)
> +++ llvm/trunk/test/tools/llvm-profdata/raw-two-profiles.test Fri Sep 12
> 16:22:55 2014
> @@ -39,11 +39,9 @@ RUN: printf '\0\0\0\0\0' >> %t-foo-padde
>  RUN: cat %t-bar.profraw > %t-bar-padded.profraw
>  RUN: printf '\0\0\0\0\0' >> %t-bar-padded.profraw
>
> -RUN: cat %t-foo.profraw %t-bar.profraw > %t-nopad.profraw
>  RUN: cat %t-foo-padded.profraw %t-bar.profraw > %t-pad-between.profraw
>  RUN: cat %t-foo-padded.profraw %t-bar-padded.profraw > %t-pad.profraw
>
> -RUN: llvm-profdata show %t-nopad.profraw -all-functions -counts |
> FileCheck %s
>  RUN: llvm-profdata show %t-pad-between.profraw -all-functions -counts |
> FileCheck %s
>  RUN: llvm-profdata show %t-pad.profraw -all-functions -counts | FileCheck
> %s
>
>
>
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