Upcast image stride to 64-bit when multiplying values. #8572
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Dimensions are limited to 16 bits which when multiplied together should fit in a 32-bit number. But the stride is (for RGBA) 4 times one dimension *and* both index and stride are signed (which is 31 bits), so it can overflow and become negative. This makes any access to a high enough index go to somewhere before the start of the buffer. Fixes matplotlib#8558.
tacaswell
approved these changes
May 5, 2017
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Makes sense to me. |
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If there's a way to add a test, that would be ideal. However, allocating that much memory as part of the test suite would be -- um -- obnoxious to say the least. |
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Also, to be a "good citizen", we should probably send this patch to the agg24-svn project upstream on sourceforge. |
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Don't think there's a way to add a non-obnoxious test since it requires a figure that is greater than 31-bits in total size. |
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Dimensions are limited to 16 bits which when multiplied together should
fit in a 32-bit number. But the stride is (for RGBA) 4 times one
dimension and both index and stride are signed (which is 31 bits), so
it can overflow and become negative. This makes any access to a high
enough index go to somewhere before the start of the buffer.
Fixes #8558.