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8263558: Possible NULL dereference in fast path arena free if ZapReso…
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…urceArea is true

Reviewed-by: kbarrett, coleenp
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tstuefe committed Mar 20, 2021
1 parent ab66d69 commit d2c137d
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Showing 2 changed files with 11 additions and 1 deletion.
9 changes: 8 additions & 1 deletion src/hotspot/share/memory/arena.cpp
Expand Up @@ -367,7 +367,14 @@ void* Arena::grow(size_t x, AllocFailType alloc_failmode) {

// Reallocate storage in Arena.
void *Arena::Arealloc(void* old_ptr, size_t old_size, size_t new_size, AllocFailType alloc_failmode) {
if (new_size == 0) return NULL;
if (new_size == 0) {
Afree(old_ptr, old_size); // like realloc(3)
return NULL;
}
if (old_ptr == NULL) {
assert(old_size == 0, "sanity");
return Amalloc(new_size, alloc_failmode); // as with realloc(3), a NULL old ptr is equivalent to malloc(3)
}
#ifdef ASSERT
if (UseMallocOnly) {
// always allocate a new object (otherwise we'll free this one twice)
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3 changes: 3 additions & 0 deletions src/hotspot/share/memory/arena.hpp
Expand Up @@ -184,6 +184,9 @@ class Arena : public CHeapObj<mtNone> {

// Fast delete in area. Common case is: NOP (except for storage reclaimed)
bool Afree(void *ptr, size_t size) {
if (ptr == NULL) {
return true; // as with free(3), freeing NULL is a noop.
}
#ifdef ASSERT
if (ZapResourceArea) memset(ptr, badResourceValue, size); // zap freed memory
if (UseMallocOnly) return true;
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