Fix some possible low-memory failures in regexp compilation.

newnfa() failed to set the regex error state when malloc() fails.
Several places in regcomp.c failed to check for an error after calling
subre().  Each of these mistakes could lead to null-pointer-dereference
crashes in memory-starved backends.

Report and patch by Andreas Seltenreich.  Back-patch to all branches.

2 files changed, 6 insertions, 0 deletions

diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c
index 3487734a64e..27998d688a8 100644
--- a/src/backend/regex/regc_nfa.c
+++ b/src/backend/regex/regc_nfa.c
@@ -52,7 +52,10 @@ newnfa(struct vars * v,
 
 	nfa = (struct nfa *) MALLOC(sizeof(struct nfa));
 	if (nfa == NULL)
+	{
+		ERR(REG_ESPACE);
 		return NULL;
+	}
 
 	nfa->states = NULL;
 	nfa->slast = NULL;
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 742539a90b9..38f48d5ddb8 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -942,6 +942,7 @@ parseqatom(struct vars * v,
 			NOERR();
 			assert(v->nextvalue > 0);
 			atom = subre(v, 'b', BACKR, lp, rp);
+			NOERR();
 			subno = v->nextvalue;
 			atom->subno = subno;
 			EMPTYARC(lp, rp);	/* temporarily, so there's something */
@@ -1076,6 +1077,7 @@ parseqatom(struct vars * v,
 
 	/* break remaining subRE into x{...} and what follows */
 	t = subre(v, '.', COMBINE(qprefer, atom->flags), lp, rp);
+	NOERR();
 	t->left = atom;
 	atomp = &t->left;
 
@@ -1084,6 +1086,7 @@ parseqatom(struct vars * v,
 	/* split top into prefix and remaining */
 	assert(top->op == '=' && top->left == NULL && top->right == NULL);
 	top->left = subre(v, '=', top->flags, top->begin, lp);
+	NOERR();
 	top->op = '.';
 	top->right = t;