tree 6621be5ceea5fb6b6b140df475af32100be7b626
parent ebca419199eb7fe574da5bc4975ddd0e4ccc2640
author Mitch Phillips <31459023+hctim@users.noreply.github.com> 1673375389 -0800
committer Copybara-Service <copybara-worker@google.com> 1673375787 -0800

[GWP-ASan] Fix up bad report for in-page underflow w/ UaF

Complex scenario, but reports when there's both a use-after-free and
buffer-underflow that is in-page (i.e. doesn't touch the guard page)
ended up generating a pretty bad report:

'Use After Free at 0x7ff392e88fef (18446744073709551615 bytes into a
1-byte allocation at 0x7ff392e88ff0) by thread 3836722 here:'

(note the 2^64-bytes-into-alloc, very cool and good!)

Fix up that case, and add a diagnostic about when you have both a
use-after-free and a buffer-overflow that it's probably a bogus report
(assuming the developer didn't *really* screw up and have a uaf+overflow
bug at the same time).

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D139885

GitOrigin-RevId: dcf23e13615f88bdd4975058595ee60cf1d5811c