Re: [syzbot] [net?] KMSAN: uninit-value in __llc_lookup_established

syzbot
2023-12-06T01:20:28Z

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: [net?] KMSAN: uninit-value in __llc_lookup_established
Author: eadavis@qq.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\n", skb->protocol);
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
+ return 0;
return 1;
}

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index afa5497f7c35..bff910513fc3 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1900,6 +1900,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb->protocol = eth_type_trans(skb, tun->dev);
break;
}
+ printk("sp: %d\n", skb->protocol);

/* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) {
@@ -1999,6 +2000,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,

local_bh_enable();
} else if (!IS_ENABLED(CONFIG_4KSTACKS)) {
+ printk("2sp: %d\n", skb->protocol);
tun_rx_batched(tun, tfile, skb, more);
} else {
netif_rx(skb);