libc/regex: fix two buffer underruns.

Fix some rather complex regex issues found on OpenBSD as part of some
ongoing work to fix a sed(1) bug.

Curiously the OpenBSD tests don't trigger segfaults on FreeBSD but the
bugs were confirmed by running a port of FreeBSD's regex under OpenBSD's
malloc. Huge thanks to Ingo for confirming the behavior.

Taken from:	Ingo Schwarze (through openbsd-tech 2016-05-15)
MFC after:	1 week
This commit is contained in:
Pedro F. Giffuni 2016-05-21 19:54:10 +00:00
parent c515200599
commit e9fe9edde7

View File

@ -606,9 +606,9 @@ backref(struct match *m,
return(NULL);
break;
case OBOL:
if ( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
(sp < m->endp && *(sp-1) == '\n' &&
(m->g->cflags&REG_NEWLINE)) )
if ((sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
(sp > m->offp && sp < m->endp &&
*(sp-1) == '\n' && (m->g->cflags&REG_NEWLINE)))
{ /* yes */ }
else
return(NULL);
@ -622,12 +622,9 @@ backref(struct match *m,
return(NULL);
break;
case OBOW:
if (( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
(sp < m->endp && *(sp-1) == '\n' &&
(m->g->cflags&REG_NEWLINE)) ||
(sp > m->beginp &&
!ISWORD(*(sp-1))) ) &&
(sp < m->endp && ISWORD(*sp)) )
if (sp < m->endp && ISWORD(*sp) &&
((sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
(sp > m->offp && !ISWORD(*(sp-1)))))
{ /* yes */ }
else
return(NULL);