Hi,
sqlsmith just found another crasher:
select bit '1' >> (-2^31)::int;
This is due to an integer overflow in bitshiftright()/bitshiftleft()
leading to them recursively calling each other. Patch attached.
regards,
Andreas
>From cfdc425f75da268e1c2af08f936c59f34b69e577 Mon Sep 17 00:00:00 2001
From: Andreas Seltenreich <seltenre...@gmx.de>
Date: Fri, 14 Oct 2016 20:52:52 +0200
Subject: [PATCH] Fix possible infinite recursion on bitshift.
bitshiftright() and bitshiftleft() would recursively call each other
infinitely when the user passed a MIN_INT for the shift amount due to
an integer overflow. This patch reduces a negative shift amount to
-VARBITMAXLEN to avoid overflow.
---
src/backend/utils/adt/varbit.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/backend/utils/adt/varbit.c b/src/backend/utils/adt/varbit.c
index 75e6a46..d8ecfb6 100644
--- a/src/backend/utils/adt/varbit.c
+++ b/src/backend/utils/adt/varbit.c
@@ -1387,9 +1387,15 @@ bitshiftleft(PG_FUNCTION_ARGS)
/* Negative shift is a shift to the right */
if (shft < 0)
+ {
+ /* Protect against overflow */
+ if (shft < -VARBITMAXLEN)
+ shft = -VARBITMAXLEN;
+
PG_RETURN_DATUM(DirectFunctionCall2(bitshiftright,
VarBitPGetDatum(arg),
Int32GetDatum(-shft)));
+ }
result = (VarBit *) palloc(VARSIZE(arg));
SET_VARSIZE(result, VARSIZE(arg));
@@ -1447,9 +1453,15 @@ bitshiftright(PG_FUNCTION_ARGS)
/* Negative shift is a shift to the left */
if (shft < 0)
+ {
+ /* Protect against overflow */
+ if (shft < -VARBITMAXLEN)
+ shft = -VARBITMAXLEN;
+
PG_RETURN_DATUM(DirectFunctionCall2(bitshiftleft,
VarBitPGetDatum(arg),
Int32GetDatum(-shft)));
+ }
result = (VarBit *) palloc(VARSIZE(arg));
SET_VARSIZE(result, VARSIZE(arg));
--
2.9.3
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