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Re: [PATCH, RFC] Introduce -fsanitize=use-after-scope (v2)
On Wed, Nov 2, 2016 at 2:06 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Wed, Nov 02, 2016 at 01:59:00PM +0100, Richard Biener wrote:
>> > Yeah, that is what I meant. The issue is how to report uses of such
>> > SSA_NAME when there is no memory. So, either we'd need a special runtime
>> > library entrypoint that would report uses after scope even when there is no
>> > underlying memory, or we'd need to force it at asan pass time into memory again.
>>
>> Well, there can't be any uses outside the scope -- there are no (memory) uses
>> left if we rewrite the thing into SSA. That is, the address can no
>> longer "escape".
>>
>> Of course there could have been invalid uses before the rewrite into SSA. But
>> those can be diagnosed either immediately before or after re-writing into SSA
>> at compile-time (may be in dead code regions of course).
>
> Sure, we can warn on those at compile time, but we really should arrange to
> error on those at runtime if they are ever executed, the UB happens only at
> runtime, so in dead code isn't fatal.
Then we can replace those uses with a call into the asan runtime diagnosing the
issue instead?
Richard.
> Jakub