Re: [PATCH] Detect escape of ErrorContextCallback stack pointers (and from PG_TRY() )

On Fri, 4 Sep 2020 at 14:13, Craig Ringer <craig(at)2ndquadrant(dot)com> wrote:

>
> I actually had a pretty good look around for static analysis options to
> see if I could find anything that might help us out before I landed up with
> this approach.
>

Apparently not good enough.

https://clang.llvm.org/docs/analyzer/checkers.html#core-stackaddressescape-c

Using a test program:

return_stack_escape.c:14:3: warning: Address of stack memory associated
with local variable 'g' is still referred to by the global variable
'guard_ptr' upon returning to the caller. This will be a dangling reference
return do_fail;
^~~~~~~~~~~~~~
1 warning generated.

so ... that's interesting. I'll need to do some checking and verify that
it's effective on the actual problem I originally had, but if so, I shall
proceed with kicking myself now.

Handily, the same thing can be used to detect PG_TRY() escapes.

--
Craig Ringer http://www.2ndQuadrant.com/
2ndQuadrant - PostgreSQL Solutions for the Enterprise