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6cb585b13a
When opt_retain is on, slab extents remain guarded in all states, even retained. This works well if arena is never destroyed, because we anticipate those slabs will be eventually reused. But if the arena is destroyed, the slabs must be unguarded to prevent leaking guard pages.
86 lines
2.6 KiB
C
86 lines
2.6 KiB
C
#include "jemalloc/internal/jemalloc_preamble.h"
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#include "jemalloc/internal/jemalloc_internal_includes.h"
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#include "jemalloc/internal/assert.h"
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#include "jemalloc/internal/ehooks.h"
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#include "jemalloc/internal/guard.h"
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#include "jemalloc/internal/tsd.h"
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/* The sanitizer options. */
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size_t opt_san_guard_large = SAN_GUARD_LARGE_EVERY_N_EXTENTS_DEFAULT;
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size_t opt_san_guard_small = SAN_GUARD_SMALL_EVERY_N_EXTENTS_DEFAULT;
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void
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guard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap) {
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emap_deregister_boundary(tsdn, emap, edata);
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size_t size_with_guards = edata_size_get(edata);
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size_t usize = size_with_guards - PAGE_GUARDS_SIZE;
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uintptr_t guard1 = (uintptr_t)edata_base_get(edata);
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uintptr_t addr = guard1 + PAGE;
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uintptr_t guard2 = addr + usize;
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assert(edata_state_get(edata) == extent_state_active);
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ehooks_guard(tsdn, ehooks, (void *)guard1, (void *)guard2);
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/* Update the guarded addr and usable size of the edata. */
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edata_size_set(edata, usize);
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edata_addr_set(edata, (void *)addr);
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edata_guarded_set(edata, true);
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/* The new boundary will be registered on the pa_alloc path. */
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}
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static void
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unguard_pages_impl(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap,
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bool reg_emap) {
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/* Remove the inner boundary which no longer exists. */
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if (reg_emap) {
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assert(edata_state_get(edata) == extent_state_active);
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emap_deregister_boundary(tsdn, emap, edata);
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} else {
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assert(edata_state_get(edata) == extent_state_retained);
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}
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size_t size = edata_size_get(edata);
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size_t size_with_guards = size + PAGE_GUARDS_SIZE;
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uintptr_t addr = (uintptr_t)edata_base_get(edata);
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uintptr_t guard1 = addr - PAGE;
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uintptr_t guard2 = addr + size;
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ehooks_unguard(tsdn, ehooks, (void *)guard1, (void *)guard2);
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/* Update the true addr and usable size of the edata. */
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edata_size_set(edata, size_with_guards);
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edata_addr_set(edata, (void *)guard1);
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edata_guarded_set(edata, false);
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/*
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* Then re-register the outer boundary including the guards, if
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* requested.
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*/
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if (reg_emap) {
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emap_register_boundary(tsdn, emap, edata, SC_NSIZES,
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/* slab */ false);
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}
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}
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void
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unguard_pages(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata, emap_t *emap) {
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unguard_pages_impl(tsdn, ehooks, edata, emap, /* reg_emap */ true);
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}
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void
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unguard_pages_pre_destroy(tsdn_t *tsdn, ehooks_t *ehooks, edata_t *edata,
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emap_t *emap) {
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emap_assert_not_mapped(tsdn, emap, edata);
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unguard_pages_impl(tsdn, ehooks, edata, emap, /* reg_emap */ false);
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}
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void
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tsd_san_init(tsd_t *tsd) {
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*tsd_san_extents_until_guard_smallp_get(tsd) = opt_san_guard_small;
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*tsd_san_extents_until_guard_largep_get(tsd) = opt_san_guard_large;
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}
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