Credit is to "Nils Sommer of bytegeist, working with Google Project Zero".

I confirmed this myself in a Win7 32-bit VM (2048MB RAM).

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The PoC triggers a pool buffer overflow in win32k!vSolidFillRect. ​When using Special Pool we get the crash immediately on the overwrite. Without Special Pool we often get a crash in the same function, but sometimes it crashes in a different function (similar to another issue, however with a different offset). This might be a result of the memory corruption or an out-of-memory condition before the overflow is triggered. Debugger output for all three different crashes attached.
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This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.

 

no_special_pool313.txt 8.1 KB View Download

bug313.cpp 2.1 KB Download

different_crash313.txt 493 bytes View Download

special_pool_crash313.txt 8.5 KB View Download