linux-kernel - Re: [syzbot] [bpf?] [net?] general protection fault in dev_map

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Message-ID: <tencent_87499A2ED6AEFA4CB927C7C6F992F5067F06@qq.com>
Date: Wed, 27 Mar 2024 22:18:30 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+af9492708df9797198d6@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bpf?] [net?] general protection fault in dev_map_enqueue

please test null ptr deref in dev_map_enqueue

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/net/core/filter.c b/net/core/filter.c
index 8adf95765cdd..721b85aebf58 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4381,6 +4381,11 @@ static __always_inline int __xdp_do_redirect_frame(struct bpf_redirect_info *ri,
 			err = dev_map_enqueue_multi(xdpf, dev, map,
 						    ri->flags & BPF_F_EXCLUDE_INGRESS);
 		} else {
+			fwd = dev_get_by_index_rcu(dev_net(dev), ri->tgt_index);
+			if (unlikely(!fwd)) {
+				err = -EINVAL;
+				break;
+			}
 			err = dev_map_enqueue(fwd, xdpf, dev);
 		}
 		break;