Hi, Sergey,
thanks for tha patch! LGTM with a minor comment below.
From: Mike Pall <mike> Thanks to Sergey Kaplun. (cherry picked from commit e45fd4cb713b610506213692f3b55a1869febb03) `narrow_conv_backprop()` misses the stack pointer (`nc->sp`) limit check after a bunch of recursive calls that may change its value. As a result, it leads to stack-buffer-overflow during the instruction narrowing. This patch adds a missing check. Sergey Kaplun: * added the description and the test for the problem Part of tarantool/tarantool#10199 --- Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1262-fix-limit-narrow-conv-backprop Related issues: * https://github.com/tarantool/tarantool/issues/10199 * https://github.com/LuaJIT/LuaJIT/issues/1262 src/lj_opt_narrow.c | 3 +- ...62-fix-limit-narrow-conv-backprop.test.lua | 61 +++++++++++++++++++ 2 files changed, 63 insertions(+), 1 deletion(-) create mode 100644 test/tarantool-tests/lj-1262-fix-limit-narrow-conv-backprop.test.lua diff --git a/src/lj_opt_narrow.c b/src/lj_opt_narrow.c index db0da10f..6b6f20d3 100644 --- a/src/lj_opt_narrow.c +++ b/src/lj_opt_narrow.c @@ -341,7 +341,8 @@ static int narrow_conv_backprop(NarrowConv *nc, IRRef ref, int depth) NarrowIns *savesp = nc->sp; int count = narrow_conv_backprop(nc, ir->op1, depth); count += narrow_conv_backprop(nc, ir->op2, depth); - if (count <= 1) { /* Limit total number of conversions. */ + /* Limit total number of conversions. */ + if (count <= 1 && nc->sp < nc->maxsp) { *nc->sp++ = NARROWINS(IRT(ir->o, nc->t), ref); return count; } diff --git a/test/tarantool-tests/lj-1262-fix-limit-narrow-conv-backprop.test.lua b/test/tarantool-tests/lj-1262-fix-limit-narrow-conv-backprop.test.lua new file mode 100644 index 00000000..6bb4025d --- /dev/null +++ b/test/tarantool-tests/lj-1262-fix-limit-narrow-conv-backprop.test.lua @@ -0,0 +1,61 @@ +local tap = require('tap') + +-- Test file to demonstrate stack-buffer-overflow during the +-- narrowing optimization. +-- See also: https://github.com/LuaJIT/LuaJIT/issues/1262. + +local test = tap.test('lj-1262-fix-limit-narrow-conv-backprop'):skipcond({ + ['Test requires JIT enabled'] = not jit.status(), +}) + +test:plan(1) + +-- XXX: Test fails only under ASAN. +-- XXX: The original reproducer was found by fuzzer: +-- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=70779. +-- It creates a long side trace with a huge amount of ADD IRs, +-- which are recursively used in the `narrow_conv_backprop()` many +-- enough times to catch the stack-buffer-overflow. I can't +-- simplify the reproducer any more (or write it from scratch), so +-- I leave it in that state. +
I would remove a sentence "I can't simplify the reproducer ..."
from the test, because it is useful information on review and
I think it is useless for those who will use the test.
Feel free to ignore and leave as is.
+local DEFAULT_NUMBER = 1 +local tonumber = tonumber + +local always_number = function(val) + return tonumber(val) or DEFAULT_NUMBER +end + +local add = function(v1, v2) + return always_number(v1) + always_number(v2) +end + +jit.opt.start('hotloop=1', 'hotexit=1') + +local counter_0 = 0 +local counter_1 = 0 +local counter_2 = 0 +local tmp = add(nil, 'Name') +local Name0 = add(tmp, 'Name') +-- Start a long side trace here. +for _ = 0, 0, 0 do + if counter_0 > 5 then break end + counter_0 = counter_0 + 1 + + for _ = always_number(false), 1, always_number(Name0) do + if counter_1 > 5 then break end + counter_1 = counter_1 + 1 + + repeat + if counter_2 > 5 then break end + counter_2 = counter_2 + 1 + + Name0 = Name0 + Name0 + Name0 + Name0 = add(Name0, nil) + Name0 + until nil + end +end + +test:ok(true, 'no stack-buffer-overflow during narrowing') + +test:done(true)