Stream: git-wasmtime

Topic: wasmtime / issue #11975 tail-aligned atomic operations tr...

Wasmtime GitHub notifications bot (Nov 04 2025 at 09:31):

kavoc-brown opened issue #11975:

Test Case

test.wat

(module
  (memory (export "mem") 1 1 shared)
  (func (export "notify_last") (result i32)
    (memory.atomic.notify (i32.const 65532) (i32.const 0))
  )
  (func (export "wait_last") (result i32)
    (memory.atomic.wait32 (i32.const 65532) (i32.const 0) (i64.const 0))
  )
)

Steps to Reproduce

• Build the Wasmtime CLI as normal
• Run wasmtime run --invoke notify_last test.wat
• Observe the trap wasm trap: out of bounds memory access.

Expected Results

The atomic instruction should succeed and return 0, since the 4-byte window starting at 0x10000 - 4 is inside the 64KiB memory.

Actual Results

Wasmtime traps with wasm trap: out of bounds memory access while executing the instruction (notify_last).

Versions and Environment

Wasmtime version or commit: v38.0.3

Operating system: Ubuntu 24.04

Architecture: x86_64

Wasmtime GitHub notifications bot (Nov 04 2025 at 09:31):

kavoc-brown added the bug label to Issue #11975.

Wasmtime GitHub notifications bot (Nov 04 2025 at 14:46):

alexcrichton added the wasm-proposal:threads label to Issue #11975.

Wasmtime GitHub notifications bot (Nov 04 2025 at 14:46):

alexcrichton commented on issue #11975:

Thanks for the report!

Wasmtime GitHub notifications bot (Nov 04 2025 at 18:58):

alexcrichton closed issue #11975:

Test Case

test.wat

(module
  (memory (export "mem") 1 1 shared)
  (func (export "notify_last") (result i32)
    (memory.atomic.notify (i32.const 65532) (i32.const 0))
  )
  (func (export "wait_last") (result i32)
    (memory.atomic.wait32 (i32.const 65532) (i32.const 0) (i64.const 0))
  )
)

Steps to Reproduce

• Build the Wasmtime CLI as normal
• Run wasmtime run --invoke notify_last test.wat
• Observe the trap wasm trap: out of bounds memory access.

Expected Results

The atomic instruction should succeed and return 0, since the 4-byte window starting at 0x10000 - 4 is inside the 64KiB memory.

Actual Results

Wasmtime traps with wasm trap: out of bounds memory access while executing the instruction (notify_last).

Versions and Environment

Wasmtime version or commit: v38.0.3

Operating system: Ubuntu 24.04

Architecture: x86_64

Last updated: Dec 06 2025 at 06:05 UTC