We need to sanity check that the nlink size and our linksLeft counter
do match. If an rpm is badly constructed with identical inode values
for multiple hardlinked files, such an rpm will otherwise access memory
out of array bounds and cause memory corruption and crashes.

The fix is to add in the sanity check and exit if bad circumstances
are found. We need to fix the caller to check the return code too.

RP 2014/6/10

Upstream-Status: Submitted [RPM5 maintainer]

Index: rpm-5.4.14/lib/fsm.c
===================================================================
--- rpm-5.4.14.orig/lib/fsm.c
+++ rpm-5.4.14/lib/fsm.c
@@ -495,6 +495,11 @@ static int saveHardLink(/*@special@*/ /*
     }
 
     if (fsm->goal == IOSM_PKGBUILD) --fsm->li->linksLeft;
+    if (fsm->li->linksLeft > st->st_nlink) {
+	rpmlog(RPMLOG_ERR, _("Corrupted hardlinks found (count %d does not match %d), exiting.\n"), fsm->li->linksLeft, st->st_nlink);
+	return -1;
+    }
+
     fsm->li->filex[fsm->li->linksLeft] = fsm->ix;
     /*@-observertrans -dependenttrans@*/
     fsm->li->nsuffix[fsm->li->linksLeft] = fsm->nsuffix;
@@ -1878,8 +1883,13 @@ if (!(fsmGetFi(fsm)->mapflags & IOSM_PAY
 	fsm->postpone = iosmFileActionSkipped(fsm->action);
 	if (fsm->goal == IOSM_PKGINSTALL || fsm->goal == IOSM_PKGBUILD) {
 	    /*@-evalorder@*/ /* FIX: saveHardLink can modify fsm */
-	    if (S_ISREG(st->st_mode) && st->st_nlink > 1)
+	    if (S_ISREG(st->st_mode) && st->st_nlink > 1) {
 		fsm->postpone = saveHardLink(fsm);
+		if (fsm->postpone < 0) {
+		    rc = RPMRC_FAIL;
+		    break;
+		}
+	    }
 	    /*@=evalorder@*/
 	}
 if (fsmGetFi(fsm)->mapflags & IOSM_PAYLOAD_LIST) fsm->postpone = 1;