linux-kernel - Re: [syzbot] [net?] KMSAN: uninit-value in __llc_lookup

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Message-ID: <0000000000003b9a89060bd203e3@google.com>
Date:   Tue, 05 Dec 2023 23:08:05 -0800
From:   syzbot <syzbot+b5ad66046b913bc04c6f@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org
Subject: Re: [syzbot] [net?] KMSAN: uninit-value in __llc_lookup_established

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Subject: [net?] KMSAN: uninit-value in __llc_lookup_established
Author: eadavis@...com

please test uninit-value in __llc_lookup_established

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 1c41041124bd

diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
index 51bccfb00a9c..58e0b8ab41b7 100644
--- a/net/llc/llc_input.c
+++ b/net/llc/llc_input.c
@@ -126,6 +126,7 @@ static inline int llc_fixup_skb(struct sk_buff *skb)
 
 	skb->transport_header += llc_len;
 	skb_pull(skb, llc_len);
+	printk("3sp: %d, %d, %d\n", skb->protocol, htons(ETH_P_802_2), htons(ETH_P_TR_802_2));
 	if (skb->protocol == htons(ETH_P_802_2)) {
 		__be16 pdulen;
 		s32 data_size;
@@ -141,7 +142,8 @@ static inline int llc_fixup_skb(struct sk_buff *skb)
 			return 0;
 		if (unlikely(pskb_trim_rcsum(skb, data_size)))
 			return 0;
-	}
+	} else if (skb->protocol != htons(ETH_P_TR_802_2))
+		return 0;
 	return 1;
 }