Bugzilla

It seems like this DEBUG-only code here is the culprit: https://searchfox.org/mozilla-central/source/dom/canvas/WebGLContext.cpp#941

The GL packing state leaks in, causing it to write to the last offsets specified by the packing state. Since the buffer it was writing to was on the stack, when it messed up, it overwrote the stack and screwed up all the stack traces we were seeing. For now I have a tentative fix that just resets the packing state before the call to fReadPixels.

This debug code was introduced in bug 1427668.

Release and opt builds are unaffected though since this code is debug-only, which is really good news.

It seems like this DEBUG-only code here is the culprit: https://searchfox.org/mozilla-central/source/dom/canvas/WebGLContext.cpp#941

The GL packing state leaks in, causing it to write to the last offsets specified by the packing state. Since the buffer it was writing to was on the stack, when it messed up, it overwrote the stack and screwed up all the stack traces we were seeing. For now I have a tentative fix that just resets the packing state before the call to fReadPixels.

This debug code was introduced in bug 1427668.

Release and opt builds are unaffected though since this code is debug-only, so it shouldn't represent a thread to normal users, which is really good news.

It seems like this DEBUG-only code here is the culprit: https://searchfox.org/mozilla-central/source/dom/canvas/WebGLContext.cpp#941

The GL packing state leaks in, causing it to write to the last offsets specified by the packing state. Since the buffer it was writing to was on the stack, when it messed up, it overwrote the stack and screwed up all the stack traces we were seeing. For now I have a tentative fix that just resets the packing state before the call to fReadPixels.

This debug code was introduced in bug 1427668.

Release and opt builds are unaffected though since this code is debug-only, so it shouldn't represent a threat to normal users, which is really good news.