From: Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: tarantool-patches@dev.tarantool.org, Sergey Kaplun <skaplun@tarantool.org>, Maxim Kokryashkin <m.kokryashkin@tarantool.org> Subject: [Tarantool-patches] [PATCH luajit 2/2][v2] FFI: Turn FFI finalizer table into a proper GC root. Date: Tue, 9 Jul 2024 13:45:51 +0300 [thread overview] Message-ID: <de0cdcca0d34ba2c07ec836e3be8128387f4869c.1720521873.git.sergeyb@tarantool.org> (raw) In-Reply-To: <cover.1720521873.git.sergeyb@tarantool.org> From: Mike Pall <mike> Reported by Sergey Bronnikov. (cherry picked from commit f5affaa6c4e7524e661484f22f24255f9a83eb47) Previous patch fixes the problem partially because the introduced GC root may not exist at the start phase of the GC cycle. In that case, the cdata finalizer table will be collected at the end of the cycle. Access to the cdata finalizer table exhibits heap use after free. The patch is turned the finalizer table into a proper GC root. Sergey Bronnikov: * added the description and the tests for the problem Part of tarantool/tarantool#10199 --- src/lib_ffi.c | 20 +-------- src/lj_cdata.c | 2 +- src/lj_ctype.c | 12 ++++++ src/lj_ctype.h | 2 +- src/lj_gc.c | 41 ++++++++---------- src/lj_obj.h | 3 ++ src/lj_state.c | 3 ++ ...free-on-access-to-CTState-finalizer.test.c | 42 +++++++++++++++++++ 8 files changed, 81 insertions(+), 44 deletions(-) diff --git a/src/lib_ffi.c b/src/lib_ffi.c index 7ed6fc78..3c8dd77f 100644 --- a/src/lib_ffi.c +++ b/src/lib_ffi.c @@ -513,7 +513,7 @@ LJLIB_CF(ffi_new) LJLIB_REC(.) /* Handle ctype __gc metamethod. Use the fast lookup here. */ cTValue *tv = lj_tab_getinth(cts->miscmap, -(int32_t)id); if (tv && tvistab(tv) && (tv = lj_meta_fast(L, tabV(tv), MM_gc))) { - GCtab *t = cts->finalizer; + GCtab *t = tabref(G(L)->gcroot[GCROOT_FFI_FIN]); if (gcref(t->metatable)) { /* Add to finalizer table, if still enabled. */ copyTV(L, lj_tab_set(L, t, o-1), tv); @@ -762,7 +762,7 @@ LJLIB_CF(ffi_abi) LJLIB_REC(.) return 1; } -LJLIB_PUSH(top-8) LJLIB_SET(!) /* Store reference to miscmap table. */ +LJLIB_PUSH(top-7) LJLIB_SET(!) /* Store reference to miscmap table. */ LJLIB_CF(ffi_metatype) { @@ -788,8 +788,6 @@ LJLIB_CF(ffi_metatype) return 1; } -LJLIB_PUSH(top-7) LJLIB_SET(!) /* Store reference to finalizer table. */ - LJLIB_CF(ffi_gc) LJLIB_REC(.) { GCcdata *cd = ffi_checkcdata(L, 1); @@ -822,19 +820,6 @@ LJLIB_PUSH(top-2) LJLIB_SET(arch) /* ------------------------------------------------------------------------ */ -/* Create special weak-keyed finalizer table. */ -static GCtab *ffi_finalizer(lua_State *L) -{ - /* NOBARRIER: The table is new (marked white). */ - GCtab *t = lj_tab_new(L, 0, 1); - settabV(L, L->top++, t); - setgcref(t->metatable, obj2gco(t)); - setstrV(L, lj_tab_setstr(L, t, lj_str_newlit(L, "__mode")), - lj_str_newlit(L, "k")); - t->nomm = (uint8_t)(~(1u<<MM_mode)); - return t; -} - /* Register FFI module as loaded. */ static void ffi_register_module(lua_State *L) { @@ -850,7 +835,6 @@ LUALIB_API int luaopen_ffi(lua_State *L) { CTState *cts = lj_ctype_init(L); settabV(L, L->top++, (cts->miscmap = lj_tab_new(L, 0, 1))); - cts->finalizer = ffi_finalizer(L); LJ_LIB_REG(L, NULL, ffi_meta); /* NOBARRIER: basemt is a GC root. */ setgcref(basemt_it(G(L), LJ_TCDATA), obj2gco(tabV(L->top-1))); diff --git a/src/lj_cdata.c b/src/lj_cdata.c index 35d0e76a..3d6ff1cc 100644 --- a/src/lj_cdata.c +++ b/src/lj_cdata.c @@ -89,7 +89,7 @@ void LJ_FASTCALL lj_cdata_free(global_State *g, GCcdata *cd) void lj_cdata_setfin(lua_State *L, GCcdata *cd, GCobj *obj, uint32_t it) { - GCtab *t = ctype_ctsG(G(L))->finalizer; + GCtab *t = tabref(G(L)->gcroot[GCROOT_FFI_FIN]); if (gcref(t->metatable)) { /* Add cdata to finalizer table, if still enabled. */ TValue *tv, tmp; diff --git a/src/lj_ctype.c b/src/lj_ctype.c index 53b83031..c0213629 100644 --- a/src/lj_ctype.c +++ b/src/lj_ctype.c @@ -643,6 +643,18 @@ CTState *lj_ctype_init(lua_State *L) return cts; } +/* Create special weak-keyed finalizer table. */ +void lj_ctype_initfin(lua_State *L) +{ + /* NOBARRIER: The table is new (marked white). */ + GCtab *t = lj_tab_new(L, 0, 1); + setgcref(t->metatable, obj2gco(t)); + setstrV(L, lj_tab_setstr(L, t, lj_str_newlit(L, "__mode")), + lj_str_newlit(L, "k")); + t->nomm = (uint8_t)(~(1u<<MM_mode)); + setgcref(G(L)->gcroot[GCROOT_FFI_FIN], obj2gco(t)); +} + /* Free C type table and state. */ void lj_ctype_freestate(global_State *g) { diff --git a/src/lj_ctype.h b/src/lj_ctype.h index 8edbd561..2d393eb9 100644 --- a/src/lj_ctype.h +++ b/src/lj_ctype.h @@ -177,7 +177,6 @@ typedef struct CTState { MSize sizetab; /* Size of C type table. */ lua_State *L; /* Lua state (needed for errors and allocations). */ global_State *g; /* Global state. */ - GCtab *finalizer; /* Map of cdata to finalizer. */ GCtab *miscmap; /* Map of -CTypeID to metatable and cb slot to func. */ CCallback cb; /* Temporary callback state. */ CTypeID1 hash[CTHASH_SIZE]; /* Hash anchors for C type table. */ @@ -473,6 +472,7 @@ LJ_FUNC GCstr *lj_ctype_repr(lua_State *L, CTypeID id, GCstr *name); LJ_FUNC GCstr *lj_ctype_repr_int64(lua_State *L, uint64_t n, int isunsigned); LJ_FUNC GCstr *lj_ctype_repr_complex(lua_State *L, void *sp, CTSize size); LJ_FUNC CTState *lj_ctype_init(lua_State *L); +LJ_FUNC void lj_ctype_initfin(lua_State *L); LJ_FUNC void lj_ctype_freestate(global_State *g); #endif diff --git a/src/lj_gc.c b/src/lj_gc.c index 42348a34..4c222f21 100644 --- a/src/lj_gc.c +++ b/src/lj_gc.c @@ -99,9 +99,6 @@ static void gc_mark_start(global_State *g) gc_markobj(g, tabref(mainthread(g)->env)); gc_marktv(g, &g->registrytv); gc_mark_gcroot(g); -#if LJ_HASFFI - if (ctype_ctsG(g)) gc_markobj(g, ctype_ctsG(g)->finalizer); -#endif g->gc.state = GCSpropagate; } @@ -181,8 +178,7 @@ static int gc_traverse_tab(global_State *g, GCtab *t) } if (weak) { /* Weak tables are cleared in the atomic phase. */ #if LJ_HASFFI - CTState *cts = ctype_ctsG(g); - if (cts && cts->finalizer == t) { + if (gcref(g->gcroot[GCROOT_FFI_FIN]) == obj2gco(t)) { weak = (int)(~0u & ~LJ_GC_WEAKVAL); } else #endif @@ -550,7 +546,7 @@ static void gc_finalize(lua_State *L) o->gch.marked &= (uint8_t)~LJ_GC_CDATA_FIN; /* Resolve finalizer. */ setcdataV(L, &tmp, gco2cd(o)); - tv = lj_tab_set(L, ctype_ctsG(g)->finalizer, &tmp); + tv = lj_tab_set(L, tabref(g->gcroot[GCROOT_FFI_FIN]), &tmp); if (!tvisnil(tv)) { g->gc.nocdatafin = 0; copyTV(L, &tmp, tv); @@ -582,23 +578,20 @@ void lj_gc_finalize_udata(lua_State *L) void lj_gc_finalize_cdata(lua_State *L) { global_State *g = G(L); - CTState *cts = ctype_ctsG(g); - if (cts) { - GCtab *t = cts->finalizer; - Node *node = noderef(t->node); - ptrdiff_t i; - setgcrefnull(t->metatable); /* Mark finalizer table as disabled. */ - for (i = (ptrdiff_t)t->hmask; i >= 0; i--) - if (!tvisnil(&node[i].val) && tviscdata(&node[i].key)) { - GCobj *o = gcV(&node[i].key); - TValue tmp; - makewhite(g, o); - o->gch.marked &= (uint8_t)~LJ_GC_CDATA_FIN; - copyTV(L, &tmp, &node[i].val); - setnilV(&node[i].val); - gc_call_finalizer(g, L, &tmp, o); - } - } + GCtab *t = tabref(g->gcroot[GCROOT_FFI_FIN]); + Node *node = noderef(t->node); + ptrdiff_t i; + setgcrefnull(t->metatable); /* Mark finalizer table as disabled. */ + for (i = (ptrdiff_t)t->hmask; i >= 0; i--) + if (!tvisnil(&node[i].val) && tviscdata(&node[i].key)) { + GCobj *o = gcV(&node[i].key); + TValue tmp; + makewhite(g, o); + o->gch.marked &= (uint8_t)~LJ_GC_CDATA_FIN; + copyTV(L, &tmp, &node[i].val); + setnilV(&node[i].val); + gc_call_finalizer(g, L, &tmp, o); + } } #endif @@ -721,7 +714,7 @@ static size_t gc_onestep(lua_State *L) return GCFINALIZECOST; } #if LJ_HASFFI - if (!g->gc.nocdatafin) lj_tab_rehash(L, ctype_ctsG(g)->finalizer); + if (!g->gc.nocdatafin) lj_tab_rehash(L, tabref(g->gcroot[GCROOT_FFI_FIN])); #endif g->gc.state = GCSpause; /* End of GC cycle. */ g->gc.debt = 0; diff --git a/src/lj_obj.h b/src/lj_obj.h index 69e94ff2..06ea0cd0 100644 --- a/src/lj_obj.h +++ b/src/lj_obj.h @@ -580,6 +580,9 @@ typedef enum { GCROOT_BASEMT_NUM = GCROOT_BASEMT + ~LJ_TNUMX, GCROOT_IO_INPUT, /* Userdata for default I/O input file. */ GCROOT_IO_OUTPUT, /* Userdata for default I/O output file. */ +#if LJ_HASFFI + GCROOT_FFI_FIN, /* FFI finalizer table. */ +#endif GCROOT_MAX } GCRootID; diff --git a/src/lj_state.c b/src/lj_state.c index 01d4901a..5a920102 100644 --- a/src/lj_state.c +++ b/src/lj_state.c @@ -180,6 +180,9 @@ static TValue *cpluaopen(lua_State *L, lua_CFunction dummy, void *ud) lj_lex_init(L); fixstring(lj_err_str(L, LJ_ERR_ERRMEM)); /* Preallocate memory error msg. */ g->gc.threshold = 4*g->gc.total; +#if LJ_HASFFI + lj_ctype_initfin(L); +#endif lj_trace_initstate(g); lj_err_verify(); return NULL; diff --git a/test/tarantool-c-tests/lj-1168-heap-use-after-free-on-access-to-CTState-finalizer.test.c b/test/tarantool-c-tests/lj-1168-heap-use-after-free-on-access-to-CTState-finalizer.test.c index c388c6a7..259528cb 100644 --- a/test/tarantool-c-tests/lj-1168-heap-use-after-free-on-access-to-CTState-finalizer.test.c +++ b/test/tarantool-c-tests/lj-1168-heap-use-after-free-on-access-to-CTState-finalizer.test.c @@ -55,10 +55,52 @@ static int unmarked_finalizer_tab_gcstart(void *test_state) return TEST_EXIT_SUCCESS; } +static int +unmarked_finalizer_tab_gcsweep(void *test_state) +{ + const char buff[] = "return 1LL"; + + /* Shared Lua state is not needed. */ + (void)test_state; + + /* Setup. */ + lua_State *L = luaL_newstate(); + + /* Set GC at the start. */ + lua_gc(L, LUA_GCCOLLECT, 0); + + /* + * Default step is too big -- one step ends after the + * atomic phase. + */ + lua_gc(L, LUA_GCSETSTEPMUL, 1); + + /* Skip marking roots. */ + lua_gc(L, LUA_GCSTEP, 1); + + /* Not trigger GC during `lua_openffi()`. */ + lua_gc(L, LUA_GCSTOP, 0); + + int res = luaL_loadbufferx(L, buff, sizeof(buff) - 1, "chunk", "t"); + assert_true(res == LUA_OK); + + /* Finish GC cycle. */ + while (!lua_gc(L, LUA_GCSTEP, -1)); + + assert_true(lua_gettop(L) == 1); + + /* Teardown. */ + lua_settop(L, 0); + lua_close(L); + + return TEST_EXIT_SUCCESS; +} + int main(void) { const struct test_unit tgroup[] = { test_unit_def(unmarked_finalizer_tab_gcstart), + test_unit_def(unmarked_finalizer_tab_gcsweep), }; const int test_result = test_run_group(tgroup, NULL); -- 2.34.1
next prev parent reply other threads:[~2024-07-09 10:48 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-07-09 10:45 [Tarantool-patches] [PATCH luajit 0/2][v2] Fix cdata finalizer table Sergey Bronnikov via Tarantool-patches 2024-07-09 10:45 ` [Tarantool-patches] [PATCH luajit 1/2][v2] FFI: Treat cdata finalizer table as a GC root Sergey Bronnikov via Tarantool-patches 2024-07-09 11:52 ` Sergey Kaplun via Tarantool-patches 2024-07-09 15:43 ` Sergey Bronnikov via Tarantool-patches 2024-07-10 13:13 ` Sergey Kaplun via Tarantool-patches 2024-07-23 18:18 ` Sergey Bronnikov via Tarantool-patches 2024-08-12 13:32 ` Sergey Kaplun via Tarantool-patches 2024-08-15 7:32 ` Sergey Bronnikov via Tarantool-patches 2024-08-15 8:33 ` Sergey Kaplun via Tarantool-patches 2024-07-09 10:45 ` Sergey Bronnikov via Tarantool-patches [this message] 2024-07-09 12:14 ` [Tarantool-patches] [PATCH luajit 2/2][v2] FFI: Turn FFI finalizer table into a proper " Sergey Kaplun via Tarantool-patches 2024-07-10 11:39 ` Sergey Bronnikov via Tarantool-patches 2024-07-10 14:08 ` Sergey Kaplun via Tarantool-patches 2024-07-23 18:29 ` Sergey Bronnikov via Tarantool-patches 2024-08-12 13:17 ` Sergey Kaplun via Tarantool-patches 2024-08-15 7:34 ` Sergey Bronnikov via Tarantool-patches 2024-08-15 8:34 ` Sergey Kaplun via Tarantool-patches 2024-07-09 11:54 ` [Tarantool-patches] [PATCH luajit 0/2][v2] Fix cdata finalizer table Sergey Kaplun via Tarantool-patches 2024-07-10 11:41 ` Sergey Bronnikov via Tarantool-patches 2024-08-15 8:15 Sergey Bronnikov via Tarantool-patches 2024-08-15 8:21 ` [Tarantool-patches] [PATCH luajit 2/2][v2] FFI: Turn FFI finalizer table into a proper GC root Sergey Bronnikov via Tarantool-patches 2024-08-15 9:38 ` Maxim Kokryashkin via Tarantool-patches
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