commit 7923dbbf72da303ca1cca17efd24725668992f15
parent 81e4fce5303fdb274bc5572fb168dd766fb8208e
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 1 Nov 2023 12:00:27 -0300
Bug: Recursion in 'getobjname' can stack overflow
'getobjname' now broken in two, a basic version that handles locals,
upvalues, and constants, and a full version, which uses the basic
version to handle table accesses (globals and fields).
Diffstat:
2 files changed, 87 insertions(+), 69 deletions(-)
diff --git a/ldebug.c b/ldebug.c
@@ -417,40 +417,6 @@ LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
** =======================================================
*/
-static const char *getobjname (const Proto *p, int lastpc, int reg,
- const char **name);
-
-
-/*
-** Find a "name" for the constant 'c'.
-*/
-static void kname (const Proto *p, int c, const char **name) {
- TValue *kvalue = &p->k[c];
- *name = (ttisstring(kvalue)) ? getstr(tsvalue(kvalue)) : "?";
-}
-
-
-/*
-** Find a "name" for the register 'c'.
-*/
-static void rname (const Proto *p, int pc, int c, const char **name) {
- const char *what = getobjname(p, pc, c, name); /* search for 'c' */
- if (!(what && *what == 'c')) /* did not find a constant name? */
- *name = "?";
-}
-
-
-/*
-** Find a "name" for a 'C' value in an RK instruction.
-*/
-static void rkname (const Proto *p, int pc, Instruction i, const char **name) {
- int c = GETARG_C(i); /* key index */
- if (GETARG_k(i)) /* is 'c' a constant? */
- kname(p, c, name);
- else /* 'c' is a register */
- rname(p, pc, c, name);
-}
-
static int filterpc (int pc, int jmptarget) {
if (pc < jmptarget) /* is code conditional (inside a jump)? */
@@ -509,28 +475,29 @@ static int findsetreg (const Proto *p, int lastpc, int reg) {
/*
-** Check whether table being indexed by instruction 'i' is the
-** environment '_ENV'
+** Find a "name" for the constant 'c'.
*/
-static const char *gxf (const Proto *p, int pc, Instruction i, int isup) {
- int t = GETARG_B(i); /* table index */
- const char *name; /* name of indexed variable */
- if (isup) /* is an upvalue? */
- name = upvalname(p, t);
- else
- getobjname(p, pc, t, &name);
- return (name && strcmp(name, LUA_ENV) == 0) ? "global" : "field";
+static const char *kname (const Proto *p, int index, const char **name) {
+ TValue *kvalue = &p->k[index];
+ if (ttisstring(kvalue)) {
+ *name = getstr(tsvalue(kvalue));
+ return "constant";
+ }
+ else {
+ *name = "?";
+ return NULL;
+ }
}
-static const char *getobjname (const Proto *p, int lastpc, int reg,
- const char **name) {
- int pc;
- *name = luaF_getlocalname(p, reg + 1, lastpc);
+static const char *basicgetobjname (const Proto *p, int *ppc, int reg,
+ const char **name) {
+ int pc = *ppc;
+ *name = luaF_getlocalname(p, reg + 1, pc);
if (*name) /* is a local? */
return "local";
/* else try symbolic execution */
- pc = findsetreg(p, lastpc, reg);
+ *ppc = pc = findsetreg(p, pc, reg);
if (pc != -1) { /* could find instruction? */
Instruction i = p->code[pc];
OpCode op = GET_OPCODE(i);
@@ -538,18 +505,80 @@ static const char *getobjname (const Proto *p, int lastpc, int reg,
case OP_MOVE: {
int b = GETARG_B(i); /* move from 'b' to 'a' */
if (b < GETARG_A(i))
- return getobjname(p, pc, b, name); /* get name for 'b' */
+ return basicgetobjname(p, ppc, b, name); /* get name for 'b' */
break;
}
+ case OP_GETUPVAL: {
+ *name = upvalname(p, GETARG_B(i));
+ return "upvalue";
+ }
+ case OP_LOADK: return kname(p, GETARG_Bx(i), name);
+ case OP_LOADKX: return kname(p, GETARG_Ax(p->code[pc + 1]), name);
+ default: break;
+ }
+ }
+ return NULL; /* could not find reasonable name */
+}
+
+
+/*
+** Find a "name" for the register 'c'.
+*/
+static void rname (const Proto *p, int pc, int c, const char **name) {
+ const char *what = basicgetobjname(p, &pc, c, name); /* search for 'c' */
+ if (!(what && *what == 'c')) /* did not find a constant name? */
+ *name = "?";
+}
+
+
+/*
+** Find a "name" for a 'C' value in an RK instruction.
+*/
+static void rkname (const Proto *p, int pc, Instruction i, const char **name) {
+ int c = GETARG_C(i); /* key index */
+ if (GETARG_k(i)) /* is 'c' a constant? */
+ kname(p, c, name);
+ else /* 'c' is a register */
+ rname(p, pc, c, name);
+}
+
+
+/*
+** Check whether table being indexed by instruction 'i' is the
+** environment '_ENV'
+*/
+static const char *isEnv (const Proto *p, int pc, Instruction i, int isup) {
+ int t = GETARG_B(i); /* table index */
+ const char *name; /* name of indexed variable */
+ if (isup) /* is 't' an upvalue? */
+ name = upvalname(p, t);
+ else /* 't' is a register */
+ basicgetobjname(p, &pc, t, &name);
+ return (name && strcmp(name, LUA_ENV) == 0) ? "global" : "field";
+}
+
+
+/*
+** Extend 'basicgetobjname' to handle table accesses
+*/
+static const char *getobjname (const Proto *p, int lastpc, int reg,
+ const char **name) {
+ const char *kind = basicgetobjname(p, &lastpc, reg, name);
+ if (kind != NULL)
+ return kind;
+ else if (lastpc != -1) { /* could find instruction? */
+ Instruction i = p->code[lastpc];
+ OpCode op = GET_OPCODE(i);
+ switch (op) {
case OP_GETTABUP: {
int k = GETARG_C(i); /* key index */
kname(p, k, name);
- return gxf(p, pc, i, 1);
+ return isEnv(p, lastpc, i, 1);
}
case OP_GETTABLE: {
int k = GETARG_C(i); /* key index */
- rname(p, pc, k, name);
- return gxf(p, pc, i, 0);
+ rname(p, lastpc, k, name);
+ return isEnv(p, lastpc, i, 0);
}
case OP_GETI: {
*name = "integer index";
@@ -558,24 +587,10 @@ static const char *getobjname (const Proto *p, int lastpc, int reg,
case OP_GETFIELD: {
int k = GETARG_C(i); /* key index */
kname(p, k, name);
- return gxf(p, pc, i, 0);
- }
- case OP_GETUPVAL: {
- *name = upvalname(p, GETARG_B(i));
- return "upvalue";
- }
- case OP_LOADK:
- case OP_LOADKX: {
- int b = (op == OP_LOADK) ? GETARG_Bx(i)
- : GETARG_Ax(p->code[pc + 1]);
- if (ttisstring(&p->k[b])) {
- *name = getstr(tsvalue(&p->k[b]));
- return "constant";
- }
- break;
+ return isEnv(p, lastpc, i, 0);
}
case OP_SELF: {
- rkname(p, pc, i, name);
+ rkname(p, lastpc, i, name);
return "method";
}
default: break; /* go through to return NULL */
diff --git a/testes/errors.lua b/testes/errors.lua
@@ -121,6 +121,9 @@ assert(not string.find(doit"aaa={13}; local bbbb=1; aaa[bbbb](3)", "'bbbb'"))
checkmessage("aaa={13}; local bbbb=1; aaa[bbbb](3)", "number")
checkmessage("aaa=(1)..{}", "a table value")
+-- bug in 5.4.6
+checkmessage("a = {_ENV = {}}; print(a._ENV.x + 1)", "field 'x'")
+
_G.aaa, _G.bbbb = nil
-- calls
