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Fix access to VMMemoryDefinition::current_length on big-endian (#3013)

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The current_length member is defined as "usize" in Rust code,
but generated wasm code refers to it as if it were "u32".
While this happens to mostly work on little-endian machines
(as long as the length is < 4GB), it will always fail on
big-endian machines.

Fixed by making current_length "u32" in Rust as well, and
ensuring the actual memory size is always less than 4GB.
This commit is contained in:
Ulrich Weigand
2021-06-23 18:45:32 +02:00
committed by GitHub
parent b8c0ac72f1
commit 83007b79e3
7 changed files with 35 additions and 16 deletions
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7
crates/runtime/src/instance/allocator.rs
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@@ -309,7 +309,7 @@ fn check_memory_init_bounds(
let end = start.checked_add(init.data.len());
match end {
Some(end) if end <= memory.current_length => {
Some(end) if end <= memory.current_length as usize => {
// Initializer is in bounds
}
_ => {
@@ -382,8 +382,9 @@ fn initialize_instance(
MemoryInitialization::Paged { map, out_of_bounds } => {
for (index, pages) in map {
let memory = instance.memory(index);
let slice =
unsafe { slice::from_raw_parts_mut(memory.base, memory.current_length) };
let slice = unsafe {
slice::from_raw_parts_mut(memory.base, memory.current_length as usize)
};
for (page_index, page) in pages.iter().enumerate() {
if let Some(data) = page {