Safety checks: Add a redzoning feature.

src/arena.c

@@ -8,6 +8,7 @@
 #include "jemalloc/internal/extent_mmap.h"
 #include "jemalloc/internal/mutex.h"
 #include "jemalloc/internal/rtree.h"
+#include "jemalloc/internal/safety_check.h"
 #include "jemalloc/internal/util.h"
 
 JEMALLOC_DIAGNOSTIC_DISABLE_SPURIOUS
@@ -1531,12 +1532,16 @@ arena_palloc(tsdn_t *tsdn, arena_t *arena, size_t usize, size_t alignment,
 }
 
 void
-arena_prof_promote(tsdn_t *tsdn, const void *ptr, size_t usize) {
+arena_prof_promote(tsdn_t *tsdn, void *ptr, size_t usize) {
 	cassert(config_prof);
 	assert(ptr != NULL);
 	assert(isalloc(tsdn, ptr) == SC_LARGE_MINCLASS);
 	assert(usize <= SC_SMALL_MAXCLASS);
 
+	if (config_opt_safety_checks) {
+		safety_check_set_redzone(ptr, usize, SC_LARGE_MINCLASS);
+	}
+
 	rtree_ctx_t rtree_ctx_fallback;
 	rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn, &rtree_ctx_fallback);
 
@@ -1577,10 +1582,19 @@ arena_dalloc_promoted(tsdn_t *tsdn, void *ptr, tcache_t *tcache,
 	assert(opt_prof);
 
 	extent_t *extent = iealloc(tsdn, ptr);
-	size_t usize = arena_prof_demote(tsdn, extent, ptr);
-	if (usize <= tcache_maxclass) {
+	size_t usize = extent_usize_get(extent);
+	size_t bumped_usize = arena_prof_demote(tsdn, extent, ptr);
+	if (config_opt_safety_checks && usize < SC_LARGE_MINCLASS) {
+		/*
+		 * Currently, we only do redzoning for small sampled
+		 * allocations.
+		 */
+		assert(bumped_usize == SC_LARGE_MINCLASS);
+		safety_check_verify_redzone(ptr, usize, bumped_usize);
+	}
+	if (bumped_usize <= tcache_maxclass) {
 		tcache_dalloc_large(tsdn_tsd(tsdn), tcache, ptr,
-		    sz_size2index(usize), slow_path);
+		    sz_size2index(bumped_usize), slow_path);
 	} else {
 		large_dalloc(tsdn, extent);
 	}