ASAN builds of WebKit should not freeze when an EXC_RESOURCE is delivered

[Tuomas Karkkainen]

When a process instrumented with AddressSanitizer receives an EXC_RESOURCE, it is frozen for several minutes.

[Tuomas Karkkainen]

Created attachment 404332 [details]
proposed patch

[Mark Lam]

Comment on attachment 404332 [details]
proposed patch

View in context: https://bugs.webkit.org/attachment.cgi?id=404332&action=review

r=me with fix.

> Source/WebKit/Shared/EntryPointUtilities/Cocoa/XPCService/XPCServiceMain.mm:153
> +        // EXC_RESOURCE on ASAN builds freezes the process for several minutes: rdar://65027596
> +        if (char *disableFreezingOnExcResource = getenv("DISABLE_FREEZING_ON_EXC_RESOURCE")) {
> +            if (!strcasecmp(disableFreezingOnExcResource, "yes") || !strcasecmp(disableFreezingOnExcResource, "true") || !strcasecmp(disableFreezingOnExcResource, "1")) {
> +                int val = 1;
> +                int rc = sysctlbyname("debug.toggle_address_reuse", nullptr, 0, &val, sizeof(val));
> +                if (rc < 0)
> +                    WTFLogAlways("failed to set debug.toggle_address_reuse: %d\n", rc);
> +                else
> +                    WTFLogAlways("debug.toggle_address_reuse is now 1.\n");
> +            }
> +        }

Can you guard this with #if ASAN_ENABLED?  We don't need this for any other builds, right?

[Tuomas Karkkainen]

Ok, will do.

I was thinking other sanitizers might be affected, but looking quickly at an UBSAN build, there are no giant mappings there, so limiting it to ASAN makes sense.

[Tuomas Karkkainen]

Created attachment 404429 [details]
proposed patch

wraps the code in #if ASAN_ENABLED as requested

[EWS]

Committed r264450: <https://trac.webkit.org/changeset/264450>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 404429 [details].

[Radar WebKit Bug Importer]

<rdar://problem/65653827>