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Re: Fwd: What can a signal handler do with SIGSTKSZ?
On 1/14/19 11:18 AM, Florian Weimer wrote:
> * Szabolcs Nagy:
>
>> i think proposing sysconf(_SC_{MIN}SIGSTKSZ) for posix is the
>> right solution with the kernel providing an upper bound of the
>> stack frame in AT_MINSIGSTKSZ (as it already does on aarch64).
>
> It's still a bit nasty for process migration, but at least it should for
> VM migration. I think that would be a reasonable compromise.
>
> Of course, we'd still need a way to determine how much we should add on
> top of AT_MINSIGSTKSZ for the application developer's benefit. 8-)
The value of SIGSTKSZ seems to be a "culturally relevant detail" that will
probably be impossible to pin down to a real value.
If *I* were a developer I might expect as Zach pointed out, that I can call
every function on the list of callable AS-safe functions, at least once,
without recursion, and expect them to operate correctly.
A test case for this would therefore be a main, that register a handler
that exercises *all* functions in the AS-safe list, and then looks for
stack corruption at each execution.
The test could also be used to set the value to some accepted value for
all machines.
Can we do this in practice?
--
Cheers,
Carlos.