From 96ead306b55b19b386b1bca93f335d3209dfdd97 Mon Sep 17 00:00:00 2001 From: NHOrus Date: Tue, 5 Sep 2017 18:20:21 +0300 Subject: [PATCH] Prevent RNG overflow. Pass save under validation by pointer, so we could mess with underlying values a little. Only thing I feel we can safely and sanely modify. --- saveresume.c | 55 ++++++++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 25 deletions(-) diff --git a/saveresume.c b/saveresume.c index 799e7af..74c03d7 100644 --- a/saveresume.c +++ b/saveresume.c @@ -105,7 +105,7 @@ int resume(void) return restore(fp); } -bool is_valid(struct game_t); +bool is_valid(struct game_t*); int restore(FILE* fp) { @@ -120,13 +120,13 @@ int restore(FILE* fp) fclose(fp); if (save.version != VRSION) { rspeak(VERSION_SKEW, save.version / 10, MOD(save.version, 10), VRSION / 10, MOD(VRSION, 10)); - } else if (is_valid(save.game)) { + } else if (is_valid(&save.game)) { game = save.game; } return GO_TOP; } -bool is_valid(struct game_t valgame) +bool is_valid(struct game_t* valgame) { /* Save files can be roughly grouped into three groups: * With valid, reaceable state, with valid, but unreachable @@ -135,48 +135,53 @@ bool is_valid(struct game_t valgame) */ /* Prevent division by zero */ - if (valgame.abbnum == 0) { + if (valgame->abbnum == 0) { return false; } /* Prevent RNG substitution. Why we are saving PRNG parameters? */ - if (valgame.lcg_a != game.lcg_a || valgame.lcg_c != game.lcg_c || valgame.lcg_m != game.lcg_m) { + if (valgame->lcg_a != game.lcg_a || valgame->lcg_c != game.lcg_c || valgame->lcg_m != game.lcg_m) { return false; } + /* Check for RNG overflow. Truncate */ + if (valgame->lcg_x >= game.lcg_m) { + valgame->lcg_x %= game.lcg_m; + } + /* Bounds check for locations */ - if ( valgame.chloc < -1 || valgame.chloc > NLOCATIONS || - valgame.chloc2 < -1 || valgame.chloc2 > NLOCATIONS || - valgame.loc < -1 || valgame.loc > NLOCATIONS || - valgame.newloc < -1 || valgame.newloc > NLOCATIONS || - valgame.oldloc < -1 || valgame.oldloc > NLOCATIONS || - valgame.oldlc2 < -1 || valgame.oldlc2 > NLOCATIONS) { + if ( valgame->chloc < -1 || valgame->chloc > NLOCATIONS || + valgame->chloc2 < -1 || valgame->chloc2 > NLOCATIONS || + valgame->loc < -1 || valgame->loc > NLOCATIONS || + valgame->newloc < -1 || valgame->newloc > NLOCATIONS || + valgame->oldloc < -1 || valgame->oldloc > NLOCATIONS || + valgame->oldlc2 < -1 || valgame->oldlc2 > NLOCATIONS) { return false; } /* Bounds check for location arrays */ for (int i = 0; i <= NDWARVES; i++) { - if (valgame.dloc[i] < -1 || valgame.dloc[i] > NLOCATIONS || - valgame.odloc[i] < -1 || valgame.odloc[i] > NLOCATIONS) { + if (valgame->dloc[i] < -1 || valgame->dloc[i] > NLOCATIONS || + valgame->odloc[i] < -1 || valgame->odloc[i] > NLOCATIONS) { return false; } } for (int i = 0; i <= NOBJECTS; i++) { - if (valgame.place[i] < -1 || valgame.place[i] > NLOCATIONS || - valgame.fixed[i] < -1 || valgame.fixed[i] > NLOCATIONS) { + if (valgame->place[i] < -1 || valgame->place[i] > NLOCATIONS || + valgame->fixed[i] < -1 || valgame->fixed[i] > NLOCATIONS) { return false; } } /* Bounds check for dwarves */ - if (valgame.dtotal < 0 || valgame.dtotal > NDWARVES || - valgame.dkill < 0 || valgame.dkill > NDWARVES) { + if (valgame->dtotal < 0 || valgame->dtotal > NDWARVES || + valgame->dkill < 0 || valgame->dkill > NDWARVES) { return false; } /* Validate that we didn't die too many times in save */ - if (valgame.numdie >= NDEATHS) { + if (valgame->numdie >= NDEATHS) { return false; } @@ -184,18 +189,18 @@ bool is_valid(struct game_t valgame) long temp_tally = 0; for (int treasure = 1; treasure <= NOBJECTS; treasure++) { if (objects[treasure].is_treasure) { - if (valgame.prop[treasure] == STATE_NOTFOUND) { + if (valgame->prop[treasure] == STATE_NOTFOUND) { ++temp_tally; } } } - if (temp_tally != valgame.tally) { + if (temp_tally != valgame->tally) { return false; } /* Check that properties of objects aren't beyond expected */ for (obj_t obj = 0; obj <= NOBJECTS; obj++) { - if (valgame.prop[obj] < STATE_NOTFOUND || valgame.prop[obj] > 1) { + if (valgame->prop[obj] < STATE_NOTFOUND || valgame->prop[obj] > 1) { switch (obj) { case RUG: case DRAGON: @@ -208,10 +213,10 @@ bool is_valid(struct game_t valgame) case EGGS: case VASE: case CHAIN: - if (valgame.prop[obj] == 2) // There are multiple different states, but it's convenient to clump them together + if (valgame->prop[obj] == 2) // There are multiple different states, but it's convenient to clump them together continue; case BEAR: - if (valgame.prop[BEAR] == CONTENTED_BEAR || game.prop[BEAR] == BEAR_DEAD) + if (valgame->prop[BEAR] == CONTENTED_BEAR || valgame->prop[BEAR] == BEAR_DEAD) continue; default: return false; @@ -221,12 +226,12 @@ bool is_valid(struct game_t valgame) /* Check that values in linked lists for objects in locations are inside bounds */ for (loc_t loc = LOC_NOWHERE; loc <= NLOCATIONS; loc++) { - if (valgame.atloc[loc] < NO_OBJECT || valgame.atloc[loc] > NOBJECTS * 2) { + if (valgame->atloc[loc] < NO_OBJECT || valgame->atloc[loc] > NOBJECTS * 2) { return false; } } for (obj_t obj = 0; obj <= NOBJECTS * 2; obj++ ) { - if (valgame.link[obj] < NO_OBJECT || valgame.link[obj] > NOBJECTS * 2) { + if (valgame->link[obj] < NO_OBJECT || valgame->link[obj] > NOBJECTS * 2) { return false; } } -- 2.31.1