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fix #H7659 - accessing freed memory by cutworm()

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hmon() can destroy the weapon being used, and known_hitum() would
still pass the pointer to the freed object to cutworm().  Remember the
relevant weapon attribute before using and maybe freeing the object,
then pass that attribute instead of the whole weapon.  Also pass
'more-likely-to-cut' for axes in addition to blades.

thimonst() behaved similarly, although due to much different code
paths none of the objects that might get to hmon() were then passed to
cutworm(), so it wasn't vulnerable.  But pass 'more-likely-to-cut'
for axes instead of for blades when thrown.
This commit is contained in:
PatR
2018-12-03 18:57:01 -08:00
parent f2195c1212
commit 285023acf6
5 changed files with 25 additions and 19 deletions
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2
doc/fixes36.2
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@@ -236,6 +236,8 @@ to emphasize that it's not a light source, change description of wielded Sting
from "(glowing)" to nothing (not warm enough to feel) when blind
glowing Sting quivers if hero becomes blind and quivering Sting glows if
blindness ends; it worked for timed blindness but not for blindfold
weapon (wielded pie, egg, potion, boomerang) might be destroyed when hitting a
long worm, then freed memory was accessed to decide whether to cut it
Fixes to Post-3.6.1 Problems that Were Exposed Via git Repository

4
include/extern.h
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@@ -1,4 +1,4 @@
/* NetHack 3.6 extern.h $NHDT-Date: 1543745352 2018/12/02 10:09:12 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.664 $ */
/* NetHack 3.6 extern.h $NHDT-Date: 1543892214 2018/12/04 02:56:54 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.665 $ */
/* Copyright (c) Steve Creps, 1988. */
/* NetHack may be freely redistributed. See license for details. */
@@ -2834,7 +2834,7 @@ E void FDECL(worm_move, (struct monst *));
E void FDECL(worm_nomove, (struct monst *));
E void FDECL(wormgone, (struct monst *));
E void FDECL(wormhitu, (struct monst *));
E void FDECL(cutworm, (struct monst *, XCHAR_P, XCHAR_P, struct obj *));
E void FDECL(cutworm, (struct monst *, XCHAR_P, XCHAR_P, BOOLEAN_P));
E void FDECL(see_wsegs, (struct monst *));
E void FDECL(detect_wsegs, (struct monst *, BOOLEAN_P));
E void FDECL(save_worm, (int, int));

14
src/dothrow.c
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@@ -1,4 +1,4 @@
/* NetHack 3.6 dothrow.c $NHDT-Date: 1525012611 2018/04/29 14:36:51 $ $NHDT-Branch: master $:$NHDT-Revision: 1.137 $ */
/* NetHack 3.6 dothrow.c $NHDT-Date: 1543892215 2018/12/04 02:56:55 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.152 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2013. */
/* NetHack may be freely redistributed. See license for details. */
@@ -1652,13 +1652,16 @@ register struct obj *obj; /* thrownobj or kickedobj or uwep */
}
if (tmp >= dieroll) {
boolean wasthrown = (thrownobj != 0);
boolean wasthrown = (thrownobj != 0),
/* remember weapon attribute; hmon() might destroy obj */
chopper = is_axe(obj);
/* attack hits mon */
if (hmode == HMON_APPLIED)
u.uconduct.weaphit++;
if (hmon(mon, obj, hmode, dieroll)) { /* mon still alive */
cutworm(mon, bhitpos.x, bhitpos.y, obj);
if (mon->wormno)
cutworm(mon, bhitpos.x, bhitpos.y, chopper);
}
exercise(A_DEX, TRUE);
/* if hero was swallowed and projectile killed the engulfer,
@@ -1668,8 +1671,9 @@ register struct obj *obj; /* thrownobj or kickedobj or uwep */
if (wasthrown && !thrownobj)
return 1;
/* projectiles other than magic stones
sometimes disappear when thrown */
/* projectiles other than magic stones sometimes disappear
when thrown; projectiles aren't among the types of weapon
that hmon() might have destroyed so obj is intact */
if (objects[otyp].oc_skill < P_NONE
&& objects[otyp].oc_skill > -P_BOOMERANG
&& !objects[otyp].oc_magic) {

8
src/uhitm.c
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@@ -1,4 +1,4 @@
/* NetHack 3.6 uhitm.c $NHDT-Date: 1542765366 2018/11/21 01:56:06 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.185 $ */
/* NetHack 3.6 uhitm.c $NHDT-Date: 1543892215 2018/12/04 02:56:55 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.195 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2012. */
/* NetHack may be freely redistributed. See license for details. */
@@ -449,7 +449,9 @@ int rollneeded, armorpenalty; /* for monks */
struct attack *uattk;
int dieroll;
{
register boolean malive = TRUE;
boolean malive = TRUE,
/* hmon() might destroy weapon; remember aspect for cutworm */
slice_or_chop = (weapon && (is_blade(weapon) || is_axe(weapon)));
if (override_confirmation) {
/* this may need to be generalized if weapons other than
@@ -490,7 +492,7 @@ int dieroll;
u.uconduct.weaphit = oldweaphit;
}
if (mon->wormno && *mhit)
cutworm(mon, x, y, weapon);
cutworm(mon, x, y, slice_or_chop);
}
}
return malive;

16
src/worm.c
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@@ -1,4 +1,4 @@
/* NetHack 3.6 worm.c $NHDT-Date: 1456528599 2016/02/26 23:16:39 $ $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.20 $ */
/* NetHack 3.6 worm.c $NHDT-Date: 1543892216 2018/12/04 02:56:56 $ $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.28 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2009. */
/* NetHack may be freely redistributed. See license for details. */
@@ -314,10 +314,10 @@ register struct monst *worm;
* that both halves will survive.
*/
void
cutworm(worm, x, y, weap)
cutworm(worm, x, y, cuttier)
struct monst *worm;
xchar x, y;
struct obj *weap;
boolean cuttier; /* hit is by wielded blade or axe or by thrown axe */
{
register struct wseg *curr, *new_tail;
register struct monst *new_worm;
@@ -330,12 +330,10 @@ struct obj *weap;
if (x == worm->mx && y == worm->my)
return; /* hit on head */
/* cutting goes best with a bladed weapon */
cut_chance = rnd(20); /* Normally 1-16 does not cut */
/* Normally 17-20 does */
if (weap && is_blade(weap)) /* With a blade 1- 6 does not cut */
cut_chance += 10; /* 7-20 does */
/* cutting goes best with a cuttier weapon */
cut_chance = rnd(20); /* Normally 1-16 does not cut, 17-20 does, */
if (cuttier)
cut_chance += 10; /* with a blade 1- 6 does not cut, 7-20 does. */
if (cut_chance < 17)
return; /* not good enough */