[tor-commits] [tor-browser] 47/76: Bug 1691774 - Check shmem allocation/mapping failures in ClientWebGLContext. r=jgilbert, a=RyanVM

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richard pushed a commit to branch tor-browser-91.8.0esr-11.0-1
in repository tor-browser.

commit 4ed1d7ab3cfe4cf806746d560cc6917b15bee767
Author: Andrew Osmond <aosmond at mozilla.com>
AuthorDate: Mon Mar 21 09:15:45 2022 -0400

    Bug 1691774 - Check shmem allocation/mapping failures in ClientWebGLContext. r=jgilbert, a=RyanVM
    
    We use webgl::RaiiShmem in a few places to read in pixel buffers from a
    call to the compositor process. Shmems might fail to be mapped into our
    process, probably due to virtual memory constraints, and we should check
    for that condition.
    
    Differential Revision: https://phabricator.services.mozilla.com/D136365
---
 dom/canvas/ClientWebGLContext.cpp | 27 ++++++++++++++++++++-------
 dom/canvas/ClientWebGLContext.h   |  3 ++-
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/dom/canvas/ClientWebGLContext.cpp b/dom/canvas/ClientWebGLContext.cpp
index dfe2550d047d3..7f7dc1e85c307 100644
--- a/dom/canvas/ClientWebGLContext.cpp
+++ b/dom/canvas/ClientWebGLContext.cpp
@@ -909,6 +909,7 @@ RefPtr<gfx::SourceSurface> ClientWebGLContext::GetFrontBufferSnapshot(
     }
     const auto& surfSize = res.surfSize;
     const webgl::RaiiShmem shmem{child, res.shmem};
+    if (!shmem) return nullptr;
     const auto& shmemBytes = shmem.ByteRange();
     if (!surfSize.x) return nullptr;  // Zero means failure.
 
@@ -1002,7 +1003,7 @@ RefPtr<gfx::DataSourceSurface> ClientWebGLContext::BackBufferSnapshot() {
 
     const auto desc = webgl::ReadPixelsDesc{{0, 0}, size};
     const auto range = Range<uint8_t>(map.GetData(), stride * size.y);
-    DoReadPixels(desc, range);
+    if (!DoReadPixels(desc, range)) return nullptr;
 
     const auto begin = range.begin().get();
 
@@ -3099,6 +3100,10 @@ void ClientWebGLContext::GetBufferSubData(GLenum target, GLintptr srcByteOffset,
     return;
   }
   const webgl::RaiiShmem shmem{child, rawShmem};
+  if (!shmem) {
+    EnqueueError(LOCAL_GL_OUT_OF_MEMORY, "Failed to map in sub data buffer.");
+    return;
+  }
 
   const auto shmemView = shmem.ByteRange();
   MOZ_RELEASE_ASSERT(shmemView.length() == 1 + destView.length());
@@ -4575,18 +4580,20 @@ void ClientWebGLContext::ReadPixels(GLint x, GLint y, GLsizei width,
                                           {format, type},
                                           state.mPixelPackState};
   const auto range = Range<uint8_t>(bytes, byteLen);
-  DoReadPixels(desc, range);
+  if (!DoReadPixels(desc, range)) {
+    return;
+  }
 }
 
-void ClientWebGLContext::DoReadPixels(const webgl::ReadPixelsDesc& desc,
+bool ClientWebGLContext::DoReadPixels(const webgl::ReadPixelsDesc& desc,
                                       const Range<uint8_t> dest) const {
   const auto notLost =
       mNotLost;  // Hold a strong-ref to prevent LoseContext=>UAF.
-  if (!notLost) return;
+  if (!notLost) return false;
   const auto& inProcess = notLost->inProcess;
   if (inProcess) {
     inProcess->ReadPixelsInto(desc, dest);
-    return;
+    return true;
   }
   const auto& child = notLost->outOfProcess;
   child->FlushPendingCmds();
@@ -4594,16 +4601,20 @@ void ClientWebGLContext::DoReadPixels(const webgl::ReadPixelsDesc& desc,
   if (!child->SendReadPixels(desc, dest.length(), &res)) {
     res = {};
   }
-  if (!res.byteStride) return;
+  if (!res.byteStride) return false;
   const auto& byteStride = res.byteStride;
   const auto& subrect = res.subrect;
   const webgl::RaiiShmem shmem{child, res.shmem};
   const auto& shmemBytes = shmem.ByteRange();
+  if (!shmem) {
+    EnqueueError(LOCAL_GL_OUT_OF_MEMORY, "Failed to map in back buffer.");
+    return false;
+  }
 
   uint8_t bpp;
   if (!GetBytesPerPixel(desc.pi, &bpp)) {
     MOZ_ASSERT(false);
-    return;
+    return false;
   }
 
   const auto& packing = desc.packState;
@@ -4628,6 +4639,8 @@ void ClientWebGLContext::DoReadPixels(const webgl::ReadPixelsDesc& desc,
     }
     Memcpy(destItr, srcItr, xByteSize);
   }
+
+  return true;
 }
 
 bool ClientWebGLContext::ReadPixels_SharedPrecheck(
diff --git a/dom/canvas/ClientWebGLContext.h b/dom/canvas/ClientWebGLContext.h
index 12e5d5782be49..c9f185dd1c790 100644
--- a/dom/canvas/ClientWebGLContext.h
+++ b/dom/canvas/ClientWebGLContext.h
@@ -1009,7 +1009,8 @@ class ClientWebGLContext final : public nsICanvasRenderingContextInternal,
 
  private:
   RefPtr<gfx::DataSourceSurface> BackBufferSnapshot();
-  void DoReadPixels(const webgl::ReadPixelsDesc&, Range<uint8_t>) const;
+  [[nodiscard]] bool DoReadPixels(const webgl::ReadPixelsDesc&,
+                                  Range<uint8_t>) const;
   uvec2 DrawingBufferSize();
 
   void AfterDrawCall() {

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