Add missing error check in regexp parser.

parseqatom() failed to check for an error return (NULL result) from its
recursive call to parsebranch(), and in consequence could crash with a
null-pointer dereference after an error return.  This bug has been there
since day one, but wasn't noticed before, probably because most error cases
in parsebranch() didn't actually lead to returning NULL.  Add the missing
error check, and also tweak parsebranch() to exit in a less indirect
fashion after a call to parseqatom() fails.

Report by Tomasz Karlik, fix by me.

diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 5c5a9a8cd2d91f9e57fff47fc21433a26145a949..9b3fe64807e508a5975b03cce2b243adf972ccdb 100644 (file)
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -712,6 +712,7 @@ parsebranch(struct vars * v,
 
                /* NB, recursion in parseqatom() may swallow rest of branch */
                parseqatom(v, stopper, type, lp, right, t);
+               NOERRN();
        }
 
        if (!seencontent)
@@ -1169,6 +1170,7 @@ parseqatom(struct vars * v,
                EMPTYARC(s2, rp);
                t->right = subre(v, '=', 0, s2, rp);
        }
+       NOERR();
        assert(SEE('|') || SEE(stopper) || SEE(EOS));
        t->flags |= COMBINE(t->flags, t->right->flags);
        top->flags |= COMBINE(top->flags, t->flags);