476497 - FEATURE_BUFFER_GUARD needs to be exterminated

Status: VERIFIED FIXED

(Tamarin Graveyard :: Virtual Machine, defect)

Description

[Steven Johnson]

We’re close to eliminating MIR entirely, at which point GrowableBuffer goes away... that will leave BufferGuard as the only remaining code in the VM that uses the magic cpu-exception handling code that is a pain to deal with, and can't be counted on to exist on all platforms anyway (especially small mobile devices). We need to replace the code with explicit buffer-overflow checks where appropriate.

(It's worth pointing out that the comment for FEATURE_BUFFER_GUARD says "CRUFT: this define exists only for the interm In a few days I'll toast the rest" so this was never intended to be a long-lived feature anyway...)

Comment 1

[Edwin Smith]

(In reply to comment #0)
> We need to replace the code with explicit buffer-overflow checks
> where appropriate.

I will be code-reviewing where these need to go, but if you know of some already please add comments.

Comment 2

[Edwin Smith]

Attachment: remove FEATURE_BUFFER_GUARD and related ifdefs

also removed:

AVMPLUS_MACH_EXCEPTIONS
AVMPLUS_ROSETTA

Extra manual checks not yet added anywhere.. this shouldn't land until code audit is complete and checks are added.

Comment 3

[Edwin Smith]

Attachment: remove #define/ifdef SAFE_PARSE

I've gone over the code and it looks like we already do bounds checking on the abc where we need to, and this should land asap unless we find i missed something.  

note that SAFE_PARSE was already defined all the time, even on platforms that supported FEATURE_BUFFER_GUARD.

Comment 4

[Edwin Smith]

removed FEATURE_BUFFER_GUARD
http://hg.mozilla.org/tamarin-redux/rev/42221e58f6b4

removed SAFE_PARSE
http://hg.mozilla.org/tamarin-redux/rev/0c430ad6c249