Bug 1274732 - Avoid allocate 128k buffer on stack r=mcmanus

Move the 128k buffer for brotli decompression to the heap instead of stack.
This fixes crash with musl libc which provides 80k stack by default.

MozReview-Commit-ID: 9cDlFO5eoi1

--HG--
extra : rebase_source : 8f8e28e63da24cd4dde9ed585e8223cde2e5d9f1

netwerk/streamconv/converters/nsHTTPCompressConv.cpp

@@ -165,9 +165,8 @@ nsHTTPCompressConv::BrotliHandler(nsIInputStream *stream, void *closure, const c
   nsHTTPCompressConv *self = static_cast<nsHTTPCompressConv *>(closure);
   *countRead = 0;
 
-  const uint32_t kOutSize = 128 * 1024; // just a chunk size, we call in a loop
-  unsigned char outBuffer[kOutSize];
-  unsigned char *outPtr;
+  const size_t kOutSize = 128 * 1024; // just a chunk size, we call in a loop
+  uint8_t *outPtr;
   size_t outSize;
   size_t avail = aAvail;
   BrotliResult res;
@@ -177,9 +176,15 @@ nsHTTPCompressConv::BrotliHandler(nsIInputStream *stream, void *closure, const c
     return NS_OK;
   }
 
+  auto outBuffer = MakeUniqueFallible<uint8_t[]>(kOutSize);
+  if (outBuffer == nullptr) {
+    self->mBrotli->mStatus = NS_ERROR_OUT_OF_MEMORY;
+    return self->mBrotli->mStatus;
+  }
+
   do {
     outSize = kOutSize;
-    outPtr = outBuffer;
+    outPtr = outBuffer.get();
 
     // brotli api is documented in brotli/dec/decode.h and brotli/dec/decode.c
     LOG(("nsHttpCompresssConv %p brotlihandler decompress %d\n", self, avail));
@@ -210,7 +215,7 @@ nsHTTPCompressConv::BrotliHandler(nsIInputStream *stream, void *closure, const c
       nsresult rv = self->do_OnDataAvailable(self->mBrotli->mRequest,
                                              self->mBrotli->mContext,
                                              self->mBrotli->mSourceOffset,
-                                             reinterpret_cast<const char *>(outBuffer),
+                                             reinterpret_cast<const char *>(outBuffer.get()),
                                              outSize);
       LOG(("nsHttpCompressConv %p BrotliHandler ODA rv=%x", self, rv));
       if (NS_FAILED(rv)) {