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Fix null pointer UB in GC

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This is just plain stupid: In C, it is not permitted to add zero
to a null pointer. In C++, it is permitted.
This commit is contained in:
Nikita Popov 2020-06-12 10:33:39 +02:00
parent ece375052b
commit 0949214ab3
1 changed files with 21 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

26
Zend/zend_gc.c
View file

@ -704,15 +704,17 @@ tail_call:
zval *zv, *end; zval *zv, *end;
ht = obj->handlers->get_gc(obj, &zv, &n); ht = obj->handlers->get_gc(obj, &zv, &n);
end = zv + n;
if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_BLACK))) { if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_BLACK))) {
ht = NULL; ht = NULL;
if (!n) goto next; if (!n) goto next;
end = zv + n;
while (!Z_REFCOUNTED_P(--end)) { while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) goto next; if (zv == end) goto next;
} }
} else { } else {
GC_REF_SET_BLACK(ht); GC_REF_SET_BLACK(ht);
if (!n) goto handle_ht;
end = zv + n;
} }
while (zv != end) { while (zv != end) {
if (Z_REFCOUNTED_P(zv)) { if (Z_REFCOUNTED_P(zv)) {
@ -757,6 +759,7 @@ tail_call:
goto next; goto next;
} }
handle_ht:
if (!ht->nNumUsed) goto next; if (!ht->nNumUsed) goto next;
p = ht->arData; p = ht->arData;
end = p + ht->nNumUsed; end = p + ht->nNumUsed;
@ -822,15 +825,17 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
zval *zv, *end; zval *zv, *end;
ht = obj->handlers->get_gc(obj, &zv, &n); ht = obj->handlers->get_gc(obj, &zv, &n);
end = zv + n;
if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_GREY))) { if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_GREY))) {
ht = NULL; ht = NULL;
if (!n) goto next; if (!n) goto next;
end = zv + n;
while (!Z_REFCOUNTED_P(--end)) { while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) goto next; if (zv == end) goto next;
} }
} else { } else {
GC_REF_SET_COLOR(ht, GC_GREY); GC_REF_SET_COLOR(ht, GC_GREY);
if (!n) goto handle_ht;
end = zv + n;
} }
while (zv != end) { while (zv != end) {
if (Z_REFCOUNTED_P(zv)) { if (Z_REFCOUNTED_P(zv)) {
@ -876,6 +881,7 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
goto next; goto next;
} }
handle_ht:
if (!ht->nNumUsed) goto next; if (!ht->nNumUsed) goto next;
p = ht->arData; p = ht->arData;
end = p + ht->nNumUsed; end = p + ht->nNumUsed;
@ -1006,15 +1012,17 @@ tail_call:
zval *zv, *end; zval *zv, *end;
ht = obj->handlers->get_gc(obj, &zv, &n); ht = obj->handlers->get_gc(obj, &zv, &n);
end = zv + n;
if (EXPECTED(!ht) || UNEXPECTED(!GC_REF_CHECK_COLOR(ht, GC_GREY))) { if (EXPECTED(!ht) || UNEXPECTED(!GC_REF_CHECK_COLOR(ht, GC_GREY))) {
ht = NULL; ht = NULL;
if (!n) goto next; if (!n) goto next;
end = zv + n;
while (!Z_REFCOUNTED_P(--end)) { while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) goto next; if (zv == end) goto next;
} }
} else { } else {
GC_REF_SET_COLOR(ht, GC_WHITE); GC_REF_SET_COLOR(ht, GC_WHITE);
if (!n) goto handle_ht;
end = zv + n;
} }
while (zv != end) { while (zv != end) {
if (Z_REFCOUNTED_P(zv)) { if (Z_REFCOUNTED_P(zv)) {
@ -1057,6 +1065,7 @@ tail_call:
goto next; goto next;
} }
handle_ht:
if (!ht->nNumUsed) goto next; if (!ht->nNumUsed) goto next;
p = ht->arData; p = ht->arData;
end = p + ht->nNumUsed; end = p + ht->nNumUsed;
@ -1176,15 +1185,17 @@ static int gc_collect_white(zend_refcounted *ref, uint32_t *flags, gc_stack *sta
*flags |= GC_HAS_DESTRUCTORS; *flags |= GC_HAS_DESTRUCTORS;
} }
ht = obj->handlers->get_gc(obj, &zv, &n); ht = obj->handlers->get_gc(obj, &zv, &n);
end = zv + n;
if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_BLACK))) { if (EXPECTED(!ht) || UNEXPECTED(GC_REF_CHECK_COLOR(ht, GC_BLACK))) {
ht = NULL; ht = NULL;
if (!n) goto next; if (!n) goto next;
end = zv + n;
while (!Z_REFCOUNTED_P(--end)) { while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) goto next; if (zv == end) goto next;
} }
} else { } else {
GC_REF_SET_BLACK(ht); GC_REF_SET_BLACK(ht);
if (!n) goto handle_ht;
end = zv + n;
} }
while (zv != end) { while (zv != end) {
if (Z_REFCOUNTED_P(zv)) { if (Z_REFCOUNTED_P(zv)) {
@ -1229,6 +1240,7 @@ static int gc_collect_white(zend_refcounted *ref, uint32_t *flags, gc_stack *sta
goto next; goto next;
} }
handle_ht:
if (!ht->nNumUsed) goto next; if (!ht->nNumUsed) goto next;
p = ht->arData; p = ht->arData;
end = p + ht->nNumUsed; end = p + ht->nNumUsed;
@ -1351,12 +1363,15 @@ tail_call:
zval *zv, *end; zval *zv, *end;
ht = obj->handlers->get_gc(obj, &zv, &n); ht = obj->handlers->get_gc(obj, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) { if (EXPECTED(!ht)) {
if (!n) return count; if (!n) return count;
end = zv + n;
while (!Z_REFCOUNTED_P(--end)) { while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) return count; if (zv == end) return count;
} }
} else {
if (!n) goto handle_ht;
end = zv + n;
} }
while (zv != end) { while (zv != end) {
if (Z_REFCOUNTED_P(zv)) { if (Z_REFCOUNTED_P(zv)) {
@ -1382,6 +1397,7 @@ tail_call:
return count; return count;
} }
handle_ht:
if (!ht->nNumUsed) return count; if (!ht->nNumUsed) return count;
p = ht->arData; p = ht->arData;
end = p + ht->nNumUsed; end = p + ht->nNumUsed;