diff --git a/sys/dev/disk/sili/sili.c b/sys/dev/disk/sili/sili.c
--- a/sys/dev/disk/sili/sili.c
+++ b/sys/dev/disk/sili/sili.c
@@ -1243,6 +1243,8 @@
 	int sgi;
 
 	KKASSERT(nsegs <= SILI_MAX_SGET);
+	if (nsegs > SILI_MAX_SGET)
+		nsegs = SILI_MAX_SGET;
 
 	sgi = 0;
 	sge = &ccb->ccb_prb->prb_sge[0];
@@ -2137,6 +2139,8 @@
 			 */
 			err_slot = log->err_regs.type &
 				   ATA_LOG_10H_TYPE_TAG_MASK;
+			if (err_slot < 0 || err_slot >= SILI_MAX_CMDS)
+				err_slot = 0;
 			ccb = &ap->ap_ccbs[err_slot];
 			if (ap->ap_expired & (1 << ccb->ccb_slot)) {
 				kprintf("%s: read NCQ error page slot=%d\n",