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It doesn’t. It’s just that dereferencing a zeroed pointer reliably crashes the program (unless you specifically do funky things with mmap) but dereferencing garbage memory as a pointer could do a lot more insidious damage.

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My point is that the developer's comment doesn't make sense. Zeroing the allocated memory doesn't change anything about overrunning the buffer.

edit: removed unnecessary examples

Haven't looked at the code, but the allocated memory could be larger than necessary to make "off-by-one" or "off-by-a-few" errors less deadly. Then zeroing it out makes it even less so. Defense in depth.

Or it's an allocation for an arena? The zeroing might help trigger 0 derefs earlier if the overrun happens for the object that are then allocated in the arena (and not by allocating more objects than the arena can provide)

This doesn't prevent overrunning the buffer -- it means that when you do overrun the buffer, it does less damage

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