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wasi: fix integer overflow in iovec bounds checks #66849

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wasi: fix integer overflow in iovec bounds checks #66849

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42 changes: 26 additions & 16 deletions src/node_wasi.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,16 @@ inline void Debug(const WASI& wasi, Args&&... args) {
} \
} while (0)

// elem_size * count is computed in size_t. A uint32_t product wraps
// (for example 0x20000000 * 8 == 0) and then skips the bounds check.
#define CHECK_ARRAY_BOUNDS_OR_RETURN(mem_size, offset, elem_size, count) \
do { \
if (!uvwasi_serdes_check_array_bounds( \
(offset), (mem_size), (elem_size), (count))) { \
return UVWASI_EOVERFLOW; \
} \
} while (0)

using v8::Array;
using v8::ArrayBuffer;
using v8::BigInt;
Expand Down Expand Up @@ -664,8 +674,8 @@ uint32_t WASI::FdPread(WASI& wasi,
iovs_len,
offset,
nread_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, iovs_len * UVWASI_SERDES_SIZE_iovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, UVWASI_SERDES_SIZE_iovec_t, iovs_len);
CHECK_BOUNDS_OR_RETURN(memory.size, nread_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_iovec_t> iovs(iovs_len);
uvwasi_errno_t err;
Expand Down Expand Up @@ -724,8 +734,8 @@ uint32_t WASI::FdPwrite(WASI& wasi,
iovs_len,
offset,
nwritten_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, iovs_len * UVWASI_SERDES_SIZE_ciovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, UVWASI_SERDES_SIZE_ciovec_t, iovs_len);
CHECK_BOUNDS_OR_RETURN(memory.size, nwritten_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_ciovec_t> iovs(iovs_len);
uvwasi_errno_t err;
Expand All @@ -752,8 +762,8 @@ uint32_t WASI::FdRead(WASI& wasi,
uint32_t iovs_len,
uint32_t nread_ptr) {
Debug(wasi, "fd_read(%d, %d, %d, %d)\n", fd, iovs_ptr, iovs_len, nread_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, iovs_len * UVWASI_SERDES_SIZE_iovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, UVWASI_SERDES_SIZE_iovec_t, iovs_len);
CHECK_BOUNDS_OR_RETURN(memory.size, nread_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_iovec_t> iovs(iovs_len);
uvwasi_errno_t err;
Expand Down Expand Up @@ -853,8 +863,8 @@ uint32_t WASI::FdWrite(WASI& wasi,
iovs_ptr,
iovs_len,
nwritten_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, iovs_len * UVWASI_SERDES_SIZE_ciovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, iovs_ptr, UVWASI_SERDES_SIZE_ciovec_t, iovs_len);
CHECK_BOUNDS_OR_RETURN(memory.size, nwritten_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_ciovec_t> iovs(iovs_len);
uvwasi_errno_t err;
Expand Down Expand Up @@ -1126,10 +1136,10 @@ uint32_t WASI::PollOneoff(WASI& wasi,
out_ptr,
nsubscriptions,
nevents_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, in_ptr, nsubscriptions * UVWASI_SERDES_SIZE_subscription_t);
CHECK_BOUNDS_OR_RETURN(
memory.size, out_ptr, nsubscriptions * UVWASI_SERDES_SIZE_event_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, in_ptr, UVWASI_SERDES_SIZE_subscription_t, nsubscriptions);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, out_ptr, UVWASI_SERDES_SIZE_event_t, nsubscriptions);
CHECK_BOUNDS_OR_RETURN(memory.size, nevents_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_subscription_t> in(nsubscriptions);
std::vector<uvwasi_event_t> out(nsubscriptions);
Expand Down Expand Up @@ -1209,8 +1219,8 @@ uint32_t WASI::SockRecv(WASI& wasi,
ri_flags,
ro_datalen_ptr,
ro_flags_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, ri_data_ptr, ri_data_len * UVWASI_SERDES_SIZE_iovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, ri_data_ptr, UVWASI_SERDES_SIZE_iovec_t, ri_data_len);
CHECK_BOUNDS_OR_RETURN(memory.size, ro_datalen_ptr, 4);
CHECK_BOUNDS_OR_RETURN(memory.size, ro_flags_ptr, 4);
std::vector<uvwasi_iovec_t> ri_data(ri_data_len);
Expand Down Expand Up @@ -1251,8 +1261,8 @@ uint32_t WASI::SockSend(WASI& wasi,
si_data_len,
si_flags,
so_datalen_ptr);
CHECK_BOUNDS_OR_RETURN(
memory.size, si_data_ptr, si_data_len * UVWASI_SERDES_SIZE_ciovec_t);
CHECK_ARRAY_BOUNDS_OR_RETURN(
memory.size, si_data_ptr, UVWASI_SERDES_SIZE_ciovec_t, si_data_len);
CHECK_BOUNDS_OR_RETURN(
memory.size, so_datalen_ptr, UVWASI_SERDES_SIZE_size_t);
std::vector<uvwasi_ciovec_t> si_data(si_data_len);
Expand Down
36 changes: 36 additions & 0 deletions test/wasi/test-wasi-iovec-overflow.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const { WASI } = require('wasi');

// deps/uvwasi/include/wasi_types.h
const UVWASI_ESUCCESS = 0;
const UVWASI_EOVERFLOW = 61;

// _start calls fd_read and stores each errno:
// 0: iovs_len 0x20000000 (0x20000000 * 8 wraps uint32_t to 0)
// 4: iovs_len 0x20000001 (wraps to 8, which fits in one page)
// 8: iovs_len 0
const bytes = Uint8Array.from([
0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x0c, 0x02, 0x60, 0x00, 0x00, 0x60, 0x04,
0x7f, 0x7f, 0x7f, 0x7f, 0x01, 0x7f, 0x02, 0x22, 0x01, 0x16, 0x77, 0x61, 0x73, 0x69, 0x5f, 0x73,
0x6e, 0x61, 0x70, 0x73, 0x68, 0x6f, 0x74, 0x5f, 0x70, 0x72, 0x65, 0x76, 0x69, 0x65, 0x77, 0x31,
0x07, 0x66, 0x64, 0x5f, 0x72, 0x65, 0x61, 0x64, 0x00, 0x01, 0x03, 0x02, 0x01, 0x00, 0x05, 0x03,
0x01, 0x00, 0x01, 0x07, 0x13, 0x02, 0x06, 0x6d, 0x65, 0x6d, 0x6f, 0x72, 0x79, 0x02, 0x00, 0x06,
0x5f, 0x73, 0x74, 0x61, 0x72, 0x74, 0x00, 0x01, 0x0a, 0x39, 0x01, 0x37, 0x00, 0x41, 0x00, 0x41,
0x00, 0x41, 0x00, 0x41, 0x80, 0x80, 0x80, 0x80, 0x02, 0x41, 0x10, 0x10, 0x00, 0x36, 0x02, 0x00,
0x41, 0x04, 0x41, 0x00, 0x41, 0x00, 0x41, 0x81, 0x80, 0x80, 0x80, 0x02, 0x41, 0x10, 0x10, 0x00,
0x36, 0x02, 0x00, 0x41, 0x08, 0x41, 0x00, 0x41, 0x00, 0x41, 0x00, 0x41, 0x10, 0x10, 0x00, 0x36,
0x02, 0x00, 0x0b,
]);

(async () => {
const wasi = new WASI({ version: 'preview1', returnOnExit: true });
const { instance } = await WebAssembly.instantiate(bytes, wasi.getImportObject());
assert.strictEqual(wasi.start(instance), 0);

const view = new DataView(instance.exports.memory.buffer);
assert.strictEqual(view.getUint32(0, true), UVWASI_EOVERFLOW);
assert.strictEqual(view.getUint32(4, true), UVWASI_EOVERFLOW);
assert.strictEqual(view.getUint32(8, true), UVWASI_ESUCCESS);
})().then(common.mustCall());
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