project-base/server-skynet-source-3rd-jemalloc
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Edata: zero stack edatas before initializing.

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This avoids some UB. No compilers take advantage of it for now, but no sense in
tempting fate.
This commit is contained in:
David Goldblatt 2020-05-13 12:42:04 -07:00 committed by David Goldblatt
parent 5dead37a9d
commit eda9c2858f
4 changed files with 12 additions and 5 deletions
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7
include/jemalloc/internal/edata.h
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@ -507,6 +507,13 @@ edata_is_head_set(edata_t *edata, bool is_head) {
((uint64_t)is_head << EDATA_BITS_IS_HEAD_SHIFT);
}
/*
* Because this function is implemented as a sequence of bitfield modifications,
* even though each individual bit is properly initialized, we technically read
* uninitialized data within it. This is mostly fine, since most callers get
* their edatas from zeroing sources, but callers who make stack edata_ts need
* to manually zero them.
*/
static inline void
edata_init(edata_t *edata, unsigned arena_ind, void *addr, size_t size,
bool slab, szind_t szind, size_t sn, extent_state_t state, bool zeroed,

2
src/emap.c
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@ -247,7 +247,7 @@ emap_split_prepare(tsdn_t *tsdn, emap_t *emap, emap_prepare_t *prepare,
* and commit state, and head status. This is a fake edata_t, used to
* facilitate a lookup.
*/
edata_t lead;
edata_t lead = {0};
edata_init(&lead, 0U, edata_addr_get(edata), size_a, false, 0, 0,
extent_state_active, false, false, false, EXTENT_NOT_HEAD);

2
src/extent_dss.c
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@ -198,7 +198,7 @@ extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
*commit = pages_decommit(ret, size);
}
if (*zero && *commit) {
edata_t edata;
edata_t edata = {0};
ehooks_t *ehooks = arena_get_ehooks(
arena);

6
test/unit/rtree.c
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@ -33,7 +33,7 @@ TEST_END
#undef SEED
TEST_BEGIN(test_rtree_extrema) {
edata_t edata_a, edata_b;
edata_t edata_a = {0}, edata_b = {0};
edata_init(&edata_a, INVALID_ARENA_IND, NULL, SC_LARGE_MINCLASS,
false, sz_size2index(SC_LARGE_MINCLASS), 0,
extent_state_active, false, false, false, EXTENT_NOT_HEAD);
@ -91,7 +91,7 @@ TEST_BEGIN(test_rtree_bits) {
uintptr_t keys[] = {PAGE, PAGE + 1,
PAGE + (((uintptr_t)1) << LG_PAGE) - 1};
edata_t edata;
edata_t edata = {0};
edata_init(&edata, INVALID_ARENA_IND, NULL, 0, false, SC_NSIZES, 0,
extent_state_active, false, false, false, EXTENT_NOT_HEAD);
@ -141,7 +141,7 @@ TEST_BEGIN(test_rtree_random) {
rtree_ctx_t rtree_ctx;
rtree_ctx_data_init(&rtree_ctx);
edata_t edata;
edata_t edata = {0};
edata_init(&edata, INVALID_ARENA_IND, NULL, 0, false, SC_NSIZES, 0,
extent_state_active, false, false, false, EXTENT_NOT_HEAD);