[src/trunk]: src/sys/arch/arm/gemini Fix potential null dereference by simply...

[andvar <andvar%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/cffe84b6d625
branches:  trunk
changeset: 376017:cffe84b6d625
user:      andvar <andvar%NetBSD.org@localhost>
date:      Fri May 26 21:40:46 2023 +0000

description:
Fix potential null dereference by simply adding last_gd != NULL check
around the code block with last_gd usage after the inner loop.
It may mainly happen on bus_dmamap_load error.
Reported by Mootja _14, 2017.

diffstat:

 sys/arch/arm/gemini/if_gpn.c |  17 ++++++++---------
 1 files changed, 8 insertions(+), 9 deletions(-)

diffs (39 lines):

diff -r da31fab2f650 -r cffe84b6d625 sys/arch/arm/gemini/if_gpn.c
--- a/sys/arch/arm/gemini/if_gpn.c      Fri May 26 20:50:21 2023 +0000
+++ b/sys/arch/arm/gemini/if_gpn.c      Fri May 26 21:40:46 2023 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: if_gpn.c,v 1.16 2022/09/17 19:49:09 thorpej Exp $ */
+/* $NetBSD: if_gpn.c,v 1.17 2023/05/26 21:40:46 andvar Exp $ */
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
  * All rights reserved.
@@ -32,7 +32,7 @@
 
 #include "opt_gemini.h"
 
-__KERNEL_RCSID(0, "$NetBSD: if_gpn.c,v 1.16 2022/09/17 19:49:09 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_gpn.c,v 1.17 2023/05/26 21:40:46 andvar Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -472,14 +472,13 @@ gpn_ifstart(struct ifnet *ifp)
                if_statinc_ref(nsr, if_opackets);
                IF_STAT_PUTREF(ifp);
 
-               /*
-                * XXX XXX 'last_gd' could be NULL
-                */
-               last_gd->gd_subtype |= GPN_EOF;
+               if (last_gd != NULL) {
+                       last_gd->gd_subtype |= GPN_EOF;
 
-               sc->sc_txactive++;
-               sc->sc_free--;
-               gemini_ipm_produce(last_gd, 1);
+                       sc->sc_txactive++;
+                       sc->sc_free--;
+                       gemini_ipm_produce(last_gd, 1);
+               }
        }
 }