Fix unsigned int overflow reported by UBSan (#761)

* Fix unsigned int overflow reported by UBSan

Please add -DOPJ_UBSAN_BUILD to CFLAGS when building with
-fsanitize=undefined,unsigned-integer-overflow

It seems clang/gcc do not allow to disable checking for block of code
other than function or file.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/lib/openjp2/pi.c b/src/lib/openjp2/pi.c
index bfee10a2..cffad668 100644
--- a/src/lib/openjp2/pi.c
+++ b/src/lib/openjp2/pi.c
@@ -747,10 +747,12 @@ static void opj_get_all_encoding_parameters(   const opj_image_t *p_image,
 		}
 
 		/* use custom size for precincts*/
-		l_level_no = l_tccp->numresolutions - 1;
+		l_level_no = l_tccp->numresolutions;
 		for (resno = 0; resno < l_tccp->numresolutions; ++resno) {
 			OPJ_UINT32 l_dx, l_dy;
 
+			--l_level_no;
+			
 			/* precinct width and height*/
 			l_pdx = l_tccp->prcw[resno];
 			l_pdy = l_tccp->prch[resno];
@@ -782,7 +784,6 @@ static void opj_get_all_encoding_parameters(   const opj_image_t *p_image,
 				*p_max_prec = l_product;
 			}
 
-			--l_level_no;
 		}
 		++l_tccp;
 		++l_img_comp;