[llvm] r270466 - llvm-dwp: More error handling around invalid compressed sections

[Richard Smith via llvm-commits]

On Mon, May 23, 2016 at 10:59 AM, David Blaikie via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: dblaikie
> Date: Mon May 23 12:59:17 2016
> New Revision: 270466
>
> URL: http://llvm.org/viewvc/llvm-project?rev=270466&view=rev
> Log:
> llvm-dwp: More error handling around invalid compressed sections
>
> Added:
>     llvm/trunk/test/tools/llvm-dwp/Inputs/empty_compressed_section.dwo
>     llvm/trunk/test/tools/llvm-dwp/Inputs/invalid_compressed.dwo
> Modified:
>     llvm/trunk/test/tools/llvm-dwp/X86/compressfail.test
>     llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp
>
> Added: llvm/trunk/test/tools/llvm-dwp/Inputs/empty_compressed_section.dwo
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-dwp/Inputs/empty_compressed_section.dwo?rev=270466&view=auto
>
> ==============================================================================
> Binary files
> llvm/trunk/test/tools/llvm-dwp/Inputs/empty_compressed_section.dwo (added)
> and llvm/trunk/test/tools/llvm-dwp/Inputs/empty_compressed_section.dwo Mon
> May 23 12:59:17 2016 differ
>
> Added: llvm/trunk/test/tools/llvm-dwp/Inputs/invalid_compressed.dwo
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-dwp/Inputs/invalid_compressed.dwo?rev=270466&view=auto
>
> ==============================================================================
> Binary files llvm/trunk/test/tools/llvm-dwp/Inputs/invalid_compressed.dwo
> (added) and llvm/trunk/test/tools/llvm-dwp/Inputs/invalid_compressed.dwo
> Mon May 23 12:59:17 2016 differ
>
> Modified: llvm/trunk/test/tools/llvm-dwp/X86/compressfail.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-dwp/X86/compressfail.test?rev=270466&r1=270465&r2=270466&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-dwp/X86/compressfail.test (original)
> +++ llvm/trunk/test/tools/llvm-dwp/X86/compressfail.test Mon May 23
> 12:59:17 2016
> @@ -1,5 +1,7 @@
>  RUN: not llvm-dwp %p/../Inputs/compressfail/a.dwo -o %t 2>&1 | FileCheck
> %s
> +RUN: not llvm-dwp %p/../Inputs/empty_compressed_section.dwo -o %t 2>&1 |
> FileCheck %s
> +RUN: not llvm-dwp %p/../Inputs/invalid_compressed.dwo -o %t 2>&1 |
> FileCheck %s
>
>  REQUIRES: zlib
>
> -CHECK: error: failure while decompressing compressed section:
> 'zdebug_info.dwo'
> +CHECK: error: failure while decompressing compressed section:
> 'zdebug_{{.*}}.dwo'
>
> Modified: llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp?rev=270466&r1=270465&r2=270466&view=diff
>
> ==============================================================================
> --- llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp (original)
> +++ llvm/trunk/tools/llvm-dwp/llvm-dwp.cpp Mon May 23 12:59:17 2016
> @@ -432,20 +432,17 @@ static Error write(MCStreamer &Out, Arra
>          return errorCodeToError(Err);
>
>        if (Name.startswith("zdebug_")) {
> +        UncompressedSections.emplace_back();
>          uint64_t OriginalSize;
>          if (!zlib::isAvailable())
>            return make_error<DWPError>("zlib not available");
> -        if (!consumeCompressedDebugSectionHeader(Contents, OriginalSize))
> +        if (!consumeCompressedDebugSectionHeader(Contents, OriginalSize)
> ||
> +            zlib::uncompress(Contents, UncompressedSections.back(),
> +                             OriginalSize) != zlib::StatusOK)
>            return make_error<DWPError>(
>                ("failure while decompressing compressed section: '" + Name
> +
>                 "\'")
>                    .str());
> -        UncompressedSections.resize(UncompressedSections.size() + 1);
> -        if (zlib::uncompress(Contents, UncompressedSections.back(),
> -                             OriginalSize) != zlib::StatusOK) {
> -          UncompressedSections.pop_back();
> -          continue;
> -        }
>          Name = Name.substr(1);
>          Contents = UncompressedSections.back();


This use of UncompressedSections looks wrong. Either:

1) you only need storage for a single string, and can reuse that storage
for each section you decompress, or
2) you are holding onto a StringRef referring to a SmallString vector
element across that vector being resized

>From code inspection, it looks like option (1): you can replace the
UncompressedSections vector with storage for a single uncompressed section.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20160525/3e3d7909/attachment.html>