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Differential D28997

Allow ssp_test:read to pass more reliably
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Authored by arichardson on Mar 1 2021, 2:55 PM.
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Reviewers
brooks
lwhsu
kevans
ngie
emaste
Commits
rGc8f8369856b5: Allow ssp_test:read to pass more reliably
rGc88c1f23a898: Allow ssp_test:read to pass more reliably
Summary

It appears that the stackframe layout can be slightly different depending on
compiler and target architecture. For example, when using CHERI LLVM for RISC-V
we can actually overflow the buffer by up to 8 bytes without SSP detecting it.
Fix this by increasing the overflow to 15 bytes.

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rG FreeBSD src repository
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Tests Not Applicable

Event Timeline

arichardson created this revision.Mar 1 2021, 2:55 PM
Herald added a reviewer: ngie. · View Herald TranscriptMar 1 2021, 2:55 PM
Herald added a subscriber: imp. · View Herald Transcript
arichardson requested review of this revision.Mar 1 2021, 2:55 PM
Harbormaster completed remote builds in B37477: Diff 84904.Mar 1 2021, 2:55 PM
arichardson added a reviewer: emaste.Mar 1 2021, 3:29 PM
emaste accepted this revision.Mar 1 2021, 3:36 PM

I think this is reasonable. I don't think we care whether SSP detects a stack overflow that overwrites only padding.

This revision is now accepted and ready to land.Mar 1 2021, 3:36 PM
emaste added inline comments.Mar 1 2021, 3:40 PM
contrib/netbsd-tests/lib/libc/ssp/t_ssp.sh
397

I wonder if this consistently works on NetBSD?

arichardson added inline comments.Mar 1 2021, 3:48 PM
contrib/netbsd-tests/lib/libc/ssp/t_ssp.sh
397

Unlikely.

ngie accepted this revision.Mar 1 2021, 6:03 PM

LGTM!

Closed by commit rGc88c1f23a898: Allow ssp_test:read to pass more reliably (authored by arichardson). · Explain WhyMar 1 2021, 7:57 PM
This revision was automatically updated to reflect the committed changes.
arichardson added a commit: rGc88c1f23a898: Allow ssp_test:read to pass more reliably.
arichardson added a commit: rGc8f8369856b5: Allow ssp_test:read to pass more reliably.Apr 22 2021, 11:09 AM

Revision Contents
Changeset List

PathSize
contrib/
netbsd-tests/
lib/
libc/
ssp/
2 lines

Diff 84920

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contrib/netbsd-tests/lib/libc/ssp/t_ssp.sh

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