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Fix MDNS crash on S2 #6193

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Mar 26, 2022
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Fix MDNS crash on S2 #6193

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5 changes: 5 additions & 0 deletions ports/espressif/common-hal/mdns/Server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,11 @@ mp_obj_t common_hal_mdns_server_find(mdns_server_obj_t *self, const char *servic
next = next->next;
}
mp_obj_tuple_t *tuple = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_results, NULL));
// The empty tuple object is shared and stored in flash so return early if
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mp_obj_new_tuple already sets the length to n, so instead of special casing num_results == 0, you can remove the assignment of len below.

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I set it to added below in case we can make the wrapper objects for all of the results. So, it may be different than the value at alloc time. Want me to make it compare the current len vs added and then set it if different?

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urp .. tuples are meant to be static in size, I'm not sure of the impact of truncating one after initial allocation. but the tuple at this point is not seen by python code, so it doesn't matter.

// we got it. Without this we'll crash when trying to set len below.
if (num_results == 0) {
return MP_OBJ_FROM_PTR(tuple);
}
next = results;
// Don't error if we're out of memory. Instead, truncate the tuple.
uint8_t added = 0;
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