malloc: Add state transitions for KASAN
ClosedPublic
Actions

Authored by markj on Mar 27 2021, 11:29 PM.

Details

Reviewers: None
Commits: rG06a53ecf2400: malloc: Add state transitions for KASAN

Summary

- Reuse some REDZONE bits to keep track of the requested and allocated
sizes, and use that to provide red zones.
- As in UMA, disable memory trashing to avoid unnecessary CPU overhead.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

markj created this revision.Mar 27 2021, 11:29 PM

Herald added a subscriber: imp. · View Herald TranscriptMar 27 2021, 11:30 PM

markj requested review of this revision.Mar 27 2021, 11:30 PM

Harbormaster completed remote builds in B38132: Diff 86418.Mar 27 2021, 11:30 PM

markj added a parent revision: D29460: execve: Mark exec argument buffers.Mar 27 2021, 11:30 PM

emaste added a subscriber: emaste.Mar 28 2021, 6:02 PM

andrew added a subscriber: andrew.Mar 29 2021, 12:14 PM

andrew added inline comments.

sys/kern/kern_malloc.c
611	Is this `#ifdef` needed?
912	Does this address space become invalid via another means in both of these paths?
1024	This doesn't look right

markj marked an inline comment as done.Mar 29 2021, 2:10 PM

markj added inline comments.

sys/kern/kern_malloc.c
912	For UMA, the region will immediately be marked invalid, so this call isn't really accomplishing anything. Note that in zfree() it is required since we are zeroing the entire allocation, including the redzone. For kmem_, the region will be marked valid (for future users of the KVA) and unmapped. I think I added this kasan_mark() call before adding state transitions to kmem_, so I marked the region valid here. Again, it is not necessary now, but is still needed in the zfree() case.
1024	Oops, indeed...