Fix address overflow bug in wasm2c #1401
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This only occurs when the immediate offset is small (`int` sized). The stack offset is `u32` and the immediate is an `int`, so the usual arithmetic conversions converts the result to a `u32`, which wraps the address before checking for overflow. There are already spec tests for overflow, but these use an offset of `4294967295`, which is `long` (at least on LP64 systems). This means that the sum's type is `u32 + long` which is `long`. This is why the tests pass. I've added additional tests for these cases here: WebAssembly/spec#1188 This fixes issue #1400.
sbc100
approved these changes
Apr 29, 2020
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This only occurs when the immediate offset is small (
intsized). Thestack offset is
u32and the immediate is anint, so the usualarithmetic conversions converts the result to a
u32, which wraps theaddress before checking for overflow.
There are already spec tests for overflow, but these use an offset of
4294967295, which islong(at least on LP64 systems). This meansthat the sum's type is
u32 + longwhich islong. This is why thetests pass. I've added additional tests for these cases here:
WebAssembly/spec#1188
This fixes issue #1400.