[Tarantool-patches] [PATCH luajit 1/2][v2] Fix embedded bytecode loader.
Sergey Bronnikov
estetus at gmail.com
Thu Aug 31 14:49:01 MSK 2023
From: Sergey Bronnikov <sergeyb at tarantool.org>
(cherry-picked from commit 820339960123dc78a7ce03edf53fcf4fdae0e55d)
The original problem is specific to x32 and is as follows: when a chunk
with a bytecode library is loaded into memory, and the address is higher
than 0x80000100, the `LexState->pe`, that contains an address of the end
of the bytecode chunk in the memory, will wrap around and become smaller
than the address in `LexState->p`, that contains an address of the
beginning of bytecode chunk in the memory. In `bcread_fill()` called by
`bcread_want()`, `memcpy()` is called with a very large size and causes
bus error on x86 and segmentation fault on ARM Android.
The problem cannot be reproduced on platforms supported by Tarantool
(ARM64, x86_64), so test doesn't reproduce a problem without a patch and
tests the patch partially.
Sergey Bronnikov:
* added the description and the test
---
src/lib_package.c | 4 +-
src/lj_bcread.c | 10 +-
src/lj_lex.c | 6 ++
src/lj_lex.h | 1 +
.../lj-549-bytecode-loader.test.lua | 96 +++++++++++++++++++
5 files changed, 110 insertions(+), 7 deletions(-)
create mode 100644 test/tarantool-tests/lj-549-bytecode-loader.test.lua
diff --git a/src/lib_package.c b/src/lib_package.c
index b49f0209..12603038 100644
--- a/src/lib_package.c
+++ b/src/lib_package.c
@@ -260,7 +260,7 @@ static int ll_loadfunc(lua_State *L, const char *path, const char *name, int r)
const char *bcdata = ll_bcsym(*reg, mksymname(L, name, SYMPREFIX_BC));
lua_pop(L, 1);
if (bcdata) {
- if (luaL_loadbuffer(L, bcdata, LJ_MAX_BUF, name) != 0)
+ if (luaL_loadbuffer(L, bcdata, ~(size_t)0, name) != 0)
return PACKAGE_ERR_LOAD;
return 0;
}
@@ -431,7 +431,7 @@ static int lj_cf_package_loader_preload(lua_State *L)
if (lua_isnil(L, -1)) { /* Not found? */
const char *bcname = mksymname(L, name, SYMPREFIX_BC);
const char *bcdata = ll_bcsym(NULL, bcname);
- if (bcdata == NULL || luaL_loadbuffer(L, bcdata, LJ_MAX_BUF, name) != 0)
+ if (bcdata == NULL || luaL_loadbuffer(L, bcdata, ~(size_t)0, name) != 0)
lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
}
return 1;
diff --git a/src/lj_bcread.c b/src/lj_bcread.c
index cddf6ff1..48ec15e4 100644
--- a/src/lj_bcread.c
+++ b/src/lj_bcread.c
@@ -79,6 +79,7 @@ static LJ_NOINLINE void bcread_fill(LexState *ls, MSize len, int need)
ls->c = -1; /* Only bad if we get called again. */
break;
}
+ if (sz >= LJ_MAX_BUF - n) lj_err_mem(ls->L);
if (n) { /* Append to buffer. */
n += (MSize)sz;
p = lj_buf_need(&ls->sb, n < len ? len : n);
@@ -90,20 +91,20 @@ static LJ_NOINLINE void bcread_fill(LexState *ls, MSize len, int need)
ls->p = buf;
ls->pe = buf + sz;
}
- } while (ls->p + len > ls->pe);
+ } while ((MSize)(ls->pe - ls->p) < len);
}
/* Need a certain number of bytes. */
static LJ_AINLINE void bcread_need(LexState *ls, MSize len)
{
- if (LJ_UNLIKELY(ls->p + len > ls->pe))
+ if (LJ_UNLIKELY((MSize)(ls->pe - ls->p) < len))
bcread_fill(ls, len, 1);
}
/* Want to read up to a certain number of bytes, but may need less. */
static LJ_AINLINE void bcread_want(LexState *ls, MSize len)
{
- if (LJ_UNLIKELY(ls->p + len > ls->pe))
+ if (LJ_UNLIKELY((MSize)(ls->pe - ls->p) < len))
bcread_fill(ls, len, 0);
}
@@ -463,8 +464,7 @@ GCproto *lj_bcread(LexState *ls)
setprotoV(L, L->top, pt);
incr_top(L);
}
- if ((int32_t)(2*(uint32_t)(ls->pe - ls->p)) > 0 ||
- L->top-1 != bcread_oldtop(L, ls))
+ if ((ls->pe != ls->p && !ls->endmark) || L->top-1 != bcread_oldtop(L, ls))
bcread_error(ls, LJ_ERR_BCBAD);
/* Pop off last prototype. */
L->top--;
diff --git a/src/lj_lex.c b/src/lj_lex.c
index cef3c683..6291705f 100644
--- a/src/lj_lex.c
+++ b/src/lj_lex.c
@@ -48,6 +48,11 @@ static LJ_NOINLINE LexChar lex_more(LexState *ls)
size_t sz;
const char *p = ls->rfunc(ls->L, ls->rdata, &sz);
if (p == NULL || sz == 0) return LEX_EOF;
+ if (sz >= LJ_MAX_BUF) {
+ if (sz != ~(size_t)0) lj_err_mem(ls->L);
+ sz = ~(uintptr_t)0 - (uintptr_t)p;
+ ls->endmark = 1;
+ }
ls->pe = p + sz;
ls->p = p + 1;
return (LexChar)(uint8_t)p[0];
@@ -408,6 +413,7 @@ int lj_lex_setup(lua_State *L, LexState *ls)
ls->lookahead = TK_eof; /* No look-ahead token. */
ls->linenumber = 1;
ls->lastline = 1;
+ ls->endmark = 0;
lex_next(ls); /* Read-ahead first char. */
if (ls->c == 0xef && ls->p + 2 <= ls->pe && (uint8_t)ls->p[0] == 0xbb &&
(uint8_t)ls->p[1] == 0xbf) { /* Skip UTF-8 BOM (if buffered). */
diff --git a/src/lj_lex.h b/src/lj_lex.h
index ae05a954..a26e504a 100644
--- a/src/lj_lex.h
+++ b/src/lj_lex.h
@@ -73,6 +73,7 @@ typedef struct LexState {
BCInsLine *bcstack; /* Stack for bytecode instructions/line numbers. */
MSize sizebcstack; /* Size of bytecode stack. */
uint32_t level; /* Syntactical nesting level. */
+ int endmark; /* Trust bytecode end marker, even if not at EOF. */
} LexState;
LJ_FUNC int lj_lex_setup(lua_State *L, LexState *ls);
diff --git a/test/tarantool-tests/lj-549-bytecode-loader.test.lua b/test/tarantool-tests/lj-549-bytecode-loader.test.lua
new file mode 100644
index 00000000..889be80a
--- /dev/null
+++ b/test/tarantool-tests/lj-549-bytecode-loader.test.lua
@@ -0,0 +1,96 @@
+local tap = require('tap')
+local ffi = require('ffi')
+local utils = require('utils')
+local test = tap.test('lj-549-bytecode-loader'):skipcond({
+ -- ['Test requires GC64 mode enabled'] = not require('ffi').abi('gc64'),
+})
+
+test:plan(1)
+
+-- Test creates a shared library with LuaJIT bytecode,
+-- loads shared library as a Lua module and checks,
+-- that no crashes eliminated.
+--
+-- $ make HOST_CC='gcc -m32' TARGET_CFLAGS='-m32' \
+-- TARGET_LDFLAGS='-m32' \
+-- TARGET_SHLDFLAGS='-m32' \
+-- -f Makefile.original
+-- $ echo 'print("test")' > a.lua
+-- $ LUA_PATH="src/?.lua;;" luajit -b a.lua a.c
+-- $ gcc -m32 -fPIC -shared a.c -o a.so
+-- $ luajit -e "require('a')"
+-- Program received signal SIGBUS, Bus error
+
+local function file_exists(fname)
+ return io.open(fname, 'r') or true and false
+end
+
+local function get_file_name(file)
+ return file:match("[^/]*$")
+end
+
+local stdout_msg = 'Lango team'
+local lua_code = ('print(%q)'):format(stdout_msg)
+local fpath = os.tmpname()
+local path_lua = ('%s.lua'):format(fpath)
+local path_c = ('%s.c'):format(fpath)
+local path_so = ('%s.so'):format(fpath)
+
+-- Create a file with a minimal Lua code.
+local fh = assert(io.open(path_lua, 'w'))
+fh:write(lua_code)
+fh:close()
+
+local module_name = assert(get_file_name(fpath))
+
+local basedir = function(path)
+ local sep = '/'
+ return path:match('(.*' .. sep .. ')') or './'
+end
+
+-- Create a C file with LuaJIT bytecode.
+-- We cannot use utils.makecmd, because command-line generated
+-- by `makecmd` contains `-e` that is incompatible with option `-b`.
+local function create_c_file(pathlua, pathc)
+ local lua_path = os.getenv('LUA_PATH')
+ local lua_bin = require('utils').exec.luacmd(arg):match('%S+')
+ local cmd_fmt = 'LUA_PATH="%s" %s -b %s %s'
+ local cmd = (cmd_fmt):format(lua_path, lua_bin, pathlua, pathc)
+ local ret = os.execute(cmd)
+ assert(ret == 0, 'create a C file with bytecode')
+end
+
+create_c_file(path_lua, path_c)
+assert(file_exists(path_c))
+
+-- Compile C source code with LuaJIT bytecode to a shared library.
+-- `-m64` is not available on ARM64, see
+-- "3.18.1 AArch64 Options in the manual",
+-- https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html
+local cflags_64 = jit.arch == 'arm64' and '-march=armv8-a' or '-m64'
+local cflags = ffi.abi('32bit') and '-m32' or cflags_64
+local cc_cmd = ('cc %s -fPIC -shared %s -o %s'):format(cflags, path_c, path_so)
+local ph = io.popen(cc_cmd)
+ph:close()
+assert(file_exists(path_so))
+
+-- Load shared library as a Lua module.
+local lua_cpath = ('"/tmp/?.so;"'):format(basedir(fpath))
+assert(file_exists(path_so))
+local cmd = utils.exec.makecmd(arg, {
+ script = ('-e "require([[%s]])"'):format(module_name),
+ env = {
+ LUA_CPATH = lua_cpath,
+ -- It is required to cleanup LUA_PATH, otherwise
+ -- LuaJIT loads Lua module, see tarantool-tests/utils/init.lua.
+ LUA_PATH = '',
+ },
+})
+local res = cmd()
+test:ok(res == stdout_msg, 'bytecode loader works')
+
+os.remove(path_lua)
+os.remove(path_c)
+os.remove(path_so)
+
+os.exit(test:check() and 0 or 1)
--
2.34.1
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