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lua fix crashes EGC failure to lock stack in concat

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Change-Id: I980637b1d8aa91d7ac0ed71fd0e7d21bda7876c4
This commit is contained in:
William Wilgus 2019-08-05 21:20:30 -05:00
parent 305ec1211f
commit 1b41e6ec43
1 changed files with 7 additions and 4 deletions
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11
apps/plugins/lua/lvm.c
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@ -290,22 +290,25 @@ int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {
void luaV_concat (lua_State *L, int total, int last) { void luaV_concat (lua_State *L, int total, int last) {
do { do {
/* Any call which does a memory allocation may trim the stack,
invalidating top unless the stack is fixed during the allocation */
StkId top = L->base + last + 1; StkId top = L->base + last + 1;
fixedstack(L);
int n = 2; /* number of elements handled in this pass (at least 2) */ int n = 2; /* number of elements handled in this pass (at least 2) */
if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) { if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
unfixedstack(L);
if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT)) { if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT)) {
/* restore 'top' pointer, since stack might have been reallocted */ /* restore 'top' pointer, since stack might have been reallocted */
top = L->base + last + 1; top = L->base + last + 1;
luaG_concaterror(L, top-2, top-1); luaG_concaterror(L, top-2, top-1);
} }
} else if (tsvalue(top-1)->len == 0) /* second op is empty? */ } else if (tsvalue(top-1)->len == 0) { /* second op is empty? */
(void)tostring(L, top - 2); /* result is first op (as string) */ (void)tostring(L, top - 2); /* result is first op (as string) */
else { } else {
/* at least two string values; get as many as possible */ /* at least two string values; get as many as possible */
size_t tl = tsvalue(top-1)->len; size_t tl = tsvalue(top-1)->len;
char *buffer; char *buffer;
int i; int i;
fixedstack(L);
/* collect total length */ /* collect total length */
for (n = 1; n < total && tostring(L, top-n-1); n++) { for (n = 1; n < total && tostring(L, top-n-1); n++) {
size_t l = tsvalue(top-n-1)->len; size_t l = tsvalue(top-n-1)->len;
@ -322,10 +325,10 @@ void luaV_concat (lua_State *L, int total, int last) {
} }
setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl)); setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
luaZ_resetbuffer(&G(L)->buff); luaZ_resetbuffer(&G(L)->buff);
unfixedstack(L);
} }
total -= n-1; /* got `n' strings to create 1 new */ total -= n-1; /* got `n' strings to create 1 new */
last -= n-1; last -= n-1;
unfixedstack(L);
} while (total > 1); /* repeat until only 1 result left */ } while (total > 1); /* repeat until only 1 result left */
} }