1 # HG changeset patch

     2 # Parent  45680ce4ca06795cbca1ea5a9ae8a7a11ab95cf1

     3 The code tries to find a codec in a list of codecs. For this it searches for a given prefix.

     4 But the prefix is of type char16_t, which means 2 bytes per character instead of 1, as was compared here.

     5 On big endian this created some false positives, as the order of bytes is different and some characters only

     6 occupy "the first" byte, having the second null'ed out.

     7 Noticed because of gtest: MediaMIMETypes.MediaCodecs

     8 

     9 Upstream bugreport: https://bugzilla.mozilla.org/show_bug.cgi?id=1573381

    10 

    11 diff -r 45680ce4ca06 -r 381102061fcc dom/media/MediaMIMETypes.cpp

    12 --- a/dom/media/MediaMIMETypes.cpp	Mon Aug 05 09:28:53 2019 +0200

    13 +++ b/dom/media/MediaMIMETypes.cpp	Tue Aug 13 07:51:27 2019 +0200

    14 @@ -87,7 +87,7 @@

    15    const size_t prefixLength = aCodecPrefix.Length();

    16    for (const auto& myCodec : Range()) {

    17      if (myCodec.Length() >= prefixLength &&

    18 -        memcmp(myCodec.Data(), aCodecPrefix.Data(), prefixLength) == 0) {

    19 +        memcmp(myCodec.Data(), aCodecPrefix.Data(), prefixLength * sizeof(char16_t)) == 0) {

    20        return true;

    21      }

    22    }