Fix module instantiation bug: out of bounds memory access

[Robbepop]

The following Wasm input was successfully instantiated in Wasmi whereas it should have failed with:

memory access out of bounds

(module
  (memory (;0;) i64 1 1)
  (func (export ""))
  (data (i64.const -1095216660480) "\ff")
)

The bug was that Wasmi was lossily converting a u64 value into a u32 and thus read the (i64.const -1095216660480) offset value as 0 instead of a huge number. This is probably an artifact from the times where Wasmi did not yet support memory64. I wonder why the fuzzing system didn't catch this (earlier).

Thanks @alexcrichton for the report.

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 71.75%. Comparing base (62cd056) to head (0cf3504).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/wasmi/src/module/instantiate/mod.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1531      +/-   ##
==========================================
+ Coverage   71.73%   71.75%   +0.01%     
==========================================
  Files         177      177              
  Lines       16523    16524       +1     
==========================================
+ Hits        11853    11857       +4     
+ Misses       4670     4667       -3     

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