T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

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

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

20
crates/runtime/src/memory.rs
View File

@@ -155,6 +155,10 @@ impl RuntimeLinearMemory for MmapMemory {
// Linear memory size would exceed the index range.
return None;
}
// FIXME: https://github.com/bytecodealliance/wasmtime/issues/3022
if new_pages == WASM_MAX_PAGES {
return None;
}
let delta_bytes = usize::try_from(delta).unwrap() * WASM_PAGE_SIZE as usize;
let prev_bytes = usize::try_from(prev_pages).unwrap() * WASM_PAGE_SIZE as usize;
@@ -194,7 +198,8 @@ impl RuntimeLinearMemory for MmapMemory {
fn vmmemory(&self) -> VMMemoryDefinition {
VMMemoryDefinition {
base: unsafe { self.mmap.alloc.as_mut_ptr().add(self.pre_guard_size) },
current_length: self.mmap.size as usize * WASM_PAGE_SIZE as usize,
current_length: u32::try_from(self.mmap.size as usize * WASM_PAGE_SIZE as usize)
.unwrap(),
}
}
}
@@ -271,6 +276,13 @@ impl Memory {
}
fn limit_new(plan: &MemoryPlan, limiter: Option<&mut dyn ResourceLimiter>) -> Result<()> {
// FIXME: https://github.com/bytecodealliance/wasmtime/issues/3022
if plan.memory.minimum == WASM_MAX_PAGES {
bail!(
"memory minimum size of {} pages exceeds memory limits",
plan.memory.minimum
);
}
if let Some(limiter) = limiter {
if !limiter.memory_growing(0, plan.memory.minimum, plan.memory.maximum) {
bail!(
@@ -362,6 +374,10 @@ impl Memory {
if new_size > maximum.unwrap_or(WASM_MAX_PAGES) {
return None;
}
// FIXME: https://github.com/bytecodealliance/wasmtime/issues/3022
if new_size == WASM_MAX_PAGES {
return None;
}
let start = usize::try_from(old_size).unwrap() * WASM_PAGE_SIZE as usize;
let len = usize::try_from(delta).unwrap() * WASM_PAGE_SIZE as usize;
@@ -381,7 +397,7 @@ impl Memory {
match self {
Memory::Static { base, size, .. } => VMMemoryDefinition {
base: base.as_ptr() as *mut _,
current_length: *size as usize * WASM_PAGE_SIZE as usize,
current_length: u32::try_from(*size as usize * WASM_PAGE_SIZE as usize).unwrap(),
},
Memory::Dynamic(mem) => mem.vmmemory(),
}