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Validate map pointer/length before allocating when lifting - #14835
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Lifting a `map<K, V>` into a `HashMap` reserved capacity for the guest-supplied length before checking that the entries actually fit in linear memory, so a guest could make the host allocate memory proportional to an arbitrary 32-bit length. This moves the allocation after the bounds, alignment and fuel checks, matching how lists are lifted. Closes bytecodealliance#14810
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Lifting a
map<K, V>into aHashMapreserved capacity for the guest-supplied length before checking that the entries actually fit in linear memory. This moves the allocation after the bounds, alignment and fuel checks, the same order lists use.For reference, before this change a guest with a single page of memory returning
(ptr = 0, len = u32::MAX)for amap<u32, u32>made the host's peak RSS jump by about 8 GiB (hashbrown initializes its control bytes) before the call failed with the bounds error. The call failed with the bounds error both before and after this change, so there's no test here; the allocation itself isn't observable from the test suite.Closes #14810