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reject size class lists longer than kNumBaseClasses in sizemap #298

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reject size class lists longer than kNumBaseClasses in sizemap #298

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13 changes: 10 additions & 3 deletions tcmalloc/sizemap.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -193,10 +193,17 @@ bool SizeMap::ValidSizeClasses(absl::Span<const SizeClassInfo> size_classes) {
if (size_classes.empty()) {
return false;
}
int num_classes = size_classes.size();
if (kHasExpandedClasses && num_classes > kNumBaseClasses) {
num_classes = kNumBaseClasses;
// SetSizeClasses writes one entry per input class into the class_to_size_,
// class_to_pages_ and num_objects_to_move_ arrays, which only have room for
// kNumBaseClasses distinct classes (the upper registers are filled later by
// replication). A longer list therefore runs past the end of those arrays,
// so reject it here instead of silently truncating only the validation.
if (size_classes.size() > kNumBaseClasses) {
TC_LOG("too many size classes %v (max %v)", size_classes.size(),
kNumBaseClasses);
return false;
}
const int num_classes = size_classes.size();

if (size_classes[0].size != 0 || size_classes[0].bytes != Bytes(0) ||
size_classes[0].num_to_move != 0) {
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