Fix off-by-one out of bounds/memory corruption bug in sobel

diff --git a/libol/trace.c b/libol/trace.c
index 4d27dd5ac03afff3d2816adc184596aeccffc734..aa077ad7336a2f25723db060794655df746aef0d 100644 (file)
--- a/libol/trace.c
+++ b/libol/trace.c
@@ -547,7 +547,7 @@ static void find_edges_canny(OLTraceCtx *ctx, uint8_t *src, unsigned int stride)
                px = ctx->sxbuf + y*ctx->aw + 2;
                py = ctx->sybuf + y*ctx->aw + 2;
                pm = ctx->smbuf + y*ctx->aw + 2;
-               for (x = 1; x < (ctx->p.width-2); x++) {
+               for (x = 2; x < (ctx->p.width-2); x++) {
                        uint32_t gm = *pm;
                        if (gm > low_t)  {
                                int16_t gx = *px;