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I know the apple documents note this for the release. But we spent a bit today at work trying to do it, and we couldn't build a test case. Has anyone actually t
by maldev 4y ago
I know the apple documents note this for the release. But we spent a bit today at work trying to do it, and we couldn't build a test case. Has anyone actually tested this? The kernel already has their own tagging system which poisons things, so I assume this is a usermode thing.
- saagarjha 4y agoMake an allocation that’s, say, 100 bytes. You’ll see it go through platform_bzero on the free path.
- maldev 4y agoAwesome! So that did work. But when trying to do 1024 bytes it doesn't zero it out. Do you happen to know what the cutoff is? I think my coworker is gonna open it up in ida, so will update back if we figure it out. EDIT: We seem to only get the zero behavior ?? < 100 < ZEROMEM <= 1008. So malloc 1009 isn't zeroing for us. And some value below 100 isn't freeing and just poisons
- saagarjha 4y agoYeah, some of the sizes don't do it. I think maybe 32 on the low end, and 1016 on the high one?