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Fix bugs with memory allocation in ego.

Browse source 
cf/cf_loop.c and share/put.c tried to read the next pointer in an
element of a linked list after freeing the element.  ud/ud_copy.c
tried to read beyond the end of the _defs_ array: it only has
_nrexpldefs_ elements, not _nrdefs_ elements.

These bugs caused core dumps on OpenBSD.  Its malloc() put _defs_ near
the end of a page, so reading beyond the end crossed into an unmapped
page.  Its free() wrote junk bytes and changed the next pointer to
0xdfdfdfdfdfdfdfdf.
This commit is contained in:
George Koehler 2016-09-09 23:37:43 -04:00
parent 8c94b1316c
commit b1d1b5e1f8
3 changed files with 11 additions and 5 deletions
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7
util/ego/cf/cf_loop.c
View file

@ -171,9 +171,12 @@ STATIC collapse_loops(loops_p)
for (li1 = Lfirst(*loops_p); li1 != (Lindex) 0; li1 = Lnext(li1,*loops_p)) {
lp1 = (loop_p) Lelem(li1);
lp1->lp_level = (short) 0;
for (li2 = Lfirst(*loops_p); li2 != (Lindex) 0;
li2 = Lnext(li2,*loops_p)) {
/* Lnext(li2,*loops_p) must happen before
* Lremove(lp2,loops_p) releases the memory for li2.
*/
for (li2 = Lfirst(*loops_p); li2 != (Lindex) 0;) {
lp2 = (loop_p) Lelem(li2);
li2 = Lnext(li2,*loops_p);
if (lp1 != lp2 && lp1->lp_entry == lp2->lp_entry) {
Ljoin(lp2->LP_BLOCKS,&lp1->LP_BLOCKS);
oldcflpx(lp2->lp_extend);

5
util/ego/share/put.c
View file

@ -386,6 +386,7 @@ putunit(kind,p,l,gf,lf)
register bblock_p b;
register short n = 0;
Lindex pi;
bblock_p nextb;
loop_p lp;
curoutp = gf;
@ -432,10 +433,12 @@ putunit(kind,p,l,gf,lf)
* after it has been written, because there may be references
* to it from other (later) blocks.
*/
for (b = p->p_start; b != (bblock_p) 0; b = b->b_next) {
for (b = p->p_start; b != (bblock_p) 0; b = nextb) {
Ldeleteset(b->b_loops);
Ldeleteset(b->b_succ);
Ldeleteset(b->b_pred);
/* Must read b->b_next before releasing b */
nextb = b->b_next;
oldbblock(b);
}
/* Release the memory for the lmap, lbmap, bmap, lpmap tables */

4
util/ego/ud/ud_copy.c
View file

@ -59,7 +59,7 @@ STATIC traverse_defs(p,action)
def_to_copynr = newtable(nrdefs);
cnt = 1;
}
if (defcnt > nrdefs) return;
if (defcnt > nrexpldefs) return;
for (b = p->p_start; b != (bblock_p) 0; b = b->b_next) {
for (l = b->b_start; l != (line_p) 0; l = l->l_next) {
if (defs[defcnt] == l) {
@ -75,7 +75,7 @@ STATIC traverse_defs(p,action)
}
}
}
if (++defcnt > nrdefs) return;
if (++defcnt > nrexpldefs) return;
}
}
}