From 8e6c371e66d9c579048fd336cc3365869486080a Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Wed, 16 Aug 2017 18:29:59 +0200
Subject: [PATCH] opj_t1_encode_cblk(): avoid uint32 overflow when numbps = 0
 (which is well defined behaviour, and is properly handled here, but better
 avoid it to detect real issues)

---
 src/lib/openjp2/t1.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/lib/openjp2/t1.c b/src/lib/openjp2/t1.c
index bd1a8800..eb5d6e0e 100644
--- a/src/lib/openjp2/t1.c
+++ b/src/lib/openjp2/t1.c
@@ -2155,6 +2155,10 @@ static void opj_t1_encode_cblk(opj_t1_t *t1,
 
     cblk->numbps = max ? (OPJ_UINT32)((opj_int_floorlog2(max) + 1) -
                                       T1_NMSEDEC_FRACBITS) : 0;
+    if (cblk->numbps == 0) {
+        cblk->totalpasses = 0;
+        return;
+    }
 
     bpno = (OPJ_INT32)(cblk->numbps - 1);
     passtype = 2;