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

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Message-ID: <000000000000c59739061dfb0c1f@google.com>
Date: Wed, 24 Jul 2024 02:39:08 -0700
From: syzbot <syzbot+44623300f057a28baf1e@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [syzbot] Re: [syzbot] [net?] [bpf?] general protection fault in __dev_flush

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Subject: Re: [syzbot] [net?] [bpf?] general protection fault in __dev_flush
Author: aha310510@...il.com

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

---
 drivers/net/tun.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9b24861464bc..022ffadae2af 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1661,7 +1661,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 				     int len, int *skb_xdp)
 {
 	struct page_frag *alloc_frag = &current->task_frag;
-	struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
 	struct bpf_prog *xdp_prog;
 	int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 	char *buf;
@@ -1701,7 +1700,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 
 	local_bh_disable();
 	rcu_read_lock();
-	bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
 	xdp_prog = rcu_dereference(tun->xdp_prog);
 	if (xdp_prog) {
 		struct xdp_buff xdp;
@@ -1730,14 +1728,12 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
 		pad = xdp.data - xdp.data_hard_start;
 		len = xdp.data_end - xdp.data;
 	}
-	bpf_net_ctx_clear(bpf_net_ctx);
 	rcu_read_unlock();
 	local_bh_enable();
 
 	return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad);
 
 out:
-	bpf_net_ctx_clear(bpf_net_ctx);
 	rcu_read_unlock();
 	local_bh_enable();
 	return NULL;
--