q66 pushed a commit to branch master. http://git.enlightenment.org/core/efl.git/commit/?id=9ca573f40f1065cc717c0c5aabb787671bab852b
commit 9ca573f40f1065cc717c0c5aabb787671bab852b Author: Daniel Kolesa <[email protected]> Date: Thu Nov 14 04:02:09 2019 +0100 eo: fix UB in the eo event code (edje_cc hangs etc.) Today I started experiencing mysterious hanging of edje_cc during build. "The French are at it again" I thought, and after spending a while bisecting, I found the culprit. It's 7f53d9158395504151e1ff3dcae715a799d913a8. So, what is happening in here? The idea here was fundamentally sound; compute a special hash value for event descriptors, taking range between 0 and 63 (on 64-bit systems) and 0 and 31 (on 32-bit systems), then use a mask sized 32-bit or 64-bit (depending on your system) and check early if to bail out from callback_call, saving some resources. So far so good. The problem is in the way the mask is handled. We're applying the hash as the shift value like, `x |= (1 << hash)`. On 32-bit systems this is okay, but on 64-bit systems, C's dumb silent coercion rules kick in, since the left side of the expression is 1, a literal with type signed int; that means our shifting range is limited to 31 and what we get is... undefined behavior. This is obviously not what we want, so take a 1ULL value as a base. The previous thing seemingly worked on x86_64 (nobody reported any issues) and interestingly it worked for me too for a while (on ppc64le), but undefined behavior can be unpredictable, so... This shouldn't need a commit message as long as this, but I'm making it proportional to the amount of time I wasted on this. --- src/lib/eo/eo_base_class.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/lib/eo/eo_base_class.c b/src/lib/eo/eo_base_class.c index 06cd48259f..8d147d3152 100644 --- a/src/lib/eo/eo_base_class.c +++ b/src/lib/eo/eo_base_class.c @@ -1263,7 +1263,7 @@ _special_event_count_inc(Eo *obj_id, Efl_Object_Data *pd, const Efl_Callback_Arr event_hash = _pointer_hash((uintptr_t) it->desc); - pd->callbacks_mask |= 1 << event_hash; + pd->callbacks_mask |= 1ULL << event_hash; EFL_OBJECT_EVENT_CB_INC(obj_id, it, pd, EFL_EVENT_CALLBACK_ADD) else EFL_OBJECT_EVENT_CB_INC(obj_id, it, pd, EFL_EVENT_CALLBACK_DEL) @@ -2009,7 +2009,7 @@ _event_callback_call(Eo *obj_id, Efl_Object_Data *pd, if (!legacy_compare) { event_hash = _pointer_hash((uintptr_t) desc); - if (!(pd->callbacks_mask & (1 << event_hash))) + if (!(pd->callbacks_mask & (1ULL << event_hash))) return EINA_TRUE; } --
