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Commit6c20bdb

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Further tweak memory management for regex DFAs.
Coverity is still unhappy after commit190c798, and after lookingcloser I think it might be onto something. The callers of newdfa()typically drop out if v->err has been set nonzero, which newdfa()is faithfully doing if it fails. However, what if v->err was alreadynonzero before we entered newdfa()? Then newdfa() could succeed andthe caller would promptly leak its result.I don't think this scenario can actually happen, but the predicate"v->err is always zero when newdfa() is called" seems difficult to beentirely sure of; there's a good deal of code that potentially couldget that wrong.It seems better to adjust the callers to directly check for a nullresult instead of relying on ISERR() tests. This is slightly cheaperthan the previous coding anyway.Lacking evidence that there's any real bug, no back-patch.
1 parent8a812e5 commit6c20bdb

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2 files changed

+10
-10
lines changed

2 files changed

+10
-10
lines changed

‎src/backend/regex/rege_dfa.c

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -604,6 +604,8 @@ lastcold(struct vars *v,
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/*
606606
* newdfa - set up a fresh DFA
607+
*
608+
* Returns NULL (and sets v->err) on failure.
607609
*/
608610
staticstructdfa*
609611
newdfa(structvars*v,

‎src/backend/regex/regexec.c

Lines changed: 8 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -351,7 +351,7 @@ getsubdfa(struct vars *v,
351351
if (d==NULL)
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{
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d=newdfa(v,&t->cnfa,&v->g->cmap,DOMALLOC);
354-
if (ISERR())
354+
if (d==NULL)
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returnNULL;
356356
/* set up additional info if this is a backref node */
357357
if (t->op=='b')
@@ -381,8 +381,6 @@ getladfa(struct vars *v,
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structsubre*sub=&v->g->lacons[n];
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v->ladfas[n]=newdfa(v,&sub->cnfa,&v->g->cmap,DOMALLOC);
384-
if (ISERR())
385-
returnNULL;
386384
/* a LACON can't contain a backref, so nothing else to do */
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}
388386
returnv->ladfas[n];
@@ -408,8 +406,8 @@ find(struct vars *v,
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409407
/* first, a shot with the search RE */
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s=newdfa(v,&v->g->search,cm,&v->dfa1);
411-
assert(!(ISERR()&&s!=NULL));
412-
NOERR();
409+
if (s==NULL)
410+
returnv->err;
413411
MDEBUG(("\nsearch at %ld\n",LOFF(v->start)));
414412
cold=NULL;
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close=shortest(v,s,v->search_start,v->search_start,v->stop,
@@ -436,8 +434,8 @@ find(struct vars *v,
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cold=NULL;
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MDEBUG(("between %ld and %ld\n",LOFF(open),LOFF(close)));
438436
d=newdfa(v,cnfa,cm,&v->dfa1);
439-
assert(!(ISERR()&&d!=NULL));
440-
NOERR();
437+
if (d==NULL)
438+
returnv->err;
441439
for (begin=open;begin <=close;begin++)
442440
{
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MDEBUG(("\nfind trying at %ld\n",LOFF(begin)));
@@ -493,11 +491,11 @@ cfind(struct vars *v,
493491
intret;
494492

495493
s=newdfa(v,&v->g->search,cm,&v->dfa1);
496-
NOERR();
494+
if (s==NULL)
495+
returnv->err;
497496
d=newdfa(v,cnfa,cm,&v->dfa2);
498-
if (ISERR())
497+
if (d==NULL)
499498
{
500-
assert(d==NULL);
501499
freedfa(s);
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returnv->err;
503501
}

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