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Message-ID: <20240119014149.60438-1-kuniyu@amazon.com>
Date: Thu, 18 Jan 2024 17:41:49 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>
CC: Paul Gortmaker <paul.gortmaker@...driver.com>, Kuniyuki Iwashima
<kuniyu@...zon.com>, Kuniyuki Iwashima <kuni1840@...il.com>,
<netdev@...r.kernel.org>,
<syzbot+b5ad66046b913bc04c6f@...kaller.appspotmail.com>
Subject: [PATCH v1 net] llc: Initialise addr before __llc_lookup().
syzbot reported an uninit-value bug below. [0]
llc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2
(0x0011), and syzbot abused the latter to trigger the bug.
write$tun(r0, &(0x7f0000000040)={@...={0x0, 0x11}, @val, @mpls={[], @llc={@...p={0xaa, 0x1, ')', "90e5dd"}}}}, 0x16)
llc_conn_handler() initialises local variables {saddr,daddr}.mac
based on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes
them to __llc_lookup().
However, the initialisation is done only when skb->protocol is
htons(ETH_P_802_2), otherwise, __llc_lookup_established() and
__llc_lookup_listener() will read garbage.
The missing initialisation existed prior to commit 211ed865108e
("net: delete all instances of special processing for token ring").
It removed the part to kick out the token ring stuff but forgot to
close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv().
Let's remove llc_tr_packet_type and complete the deprecation.
[0]:
BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90
__llc_lookup_established+0xe9d/0xf90
__llc_lookup net/llc/llc_conn.c:611 [inline]
llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791
llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206
__netif_receive_skb_one_core net/core/dev.c:5527 [inline]
__netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641
netif_receive_skb_internal net/core/dev.c:5727 [inline]
netif_receive_skb+0x58/0x660 net/core/dev.c:5786
tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555
tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002
tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2020 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x8ef/0x1490 fs/read_write.c:584
ksys_write+0x20f/0x4c0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__x64_sys_write+0x93/0xd0 fs/read_write.c:646
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Local variable daddr created at:
llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783
llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206
CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Fixes: 211ed865108e ("net: delete all instances of special processing for token ring")
Reported-by: syzbot+b5ad66046b913bc04c6f@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b5ad66046b913bc04c6f
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
include/net/llc_pdu.h | 6 ++----
net/llc/llc_core.c | 7 -------
2 files changed, 2 insertions(+), 11 deletions(-)
diff --git a/include/net/llc_pdu.h b/include/net/llc_pdu.h
index 7e73f8e5e497..1d55ba7c45be 100644
--- a/include/net/llc_pdu.h
+++ b/include/net/llc_pdu.h
@@ -262,8 +262,7 @@ static inline void llc_pdu_header_init(struct sk_buff *skb, u8 type,
*/
static inline void llc_pdu_decode_sa(struct sk_buff *skb, u8 *sa)
{
- if (skb->protocol == htons(ETH_P_802_2))
- memcpy(sa, eth_hdr(skb)->h_source, ETH_ALEN);
+ memcpy(sa, eth_hdr(skb)->h_source, ETH_ALEN);
}
/**
@@ -275,8 +274,7 @@ static inline void llc_pdu_decode_sa(struct sk_buff *skb, u8 *sa)
*/
static inline void llc_pdu_decode_da(struct sk_buff *skb, u8 *da)
{
- if (skb->protocol == htons(ETH_P_802_2))
- memcpy(da, eth_hdr(skb)->h_dest, ETH_ALEN);
+ memcpy(da, eth_hdr(skb)->h_dest, ETH_ALEN);
}
/**
diff --git a/net/llc/llc_core.c b/net/llc/llc_core.c
index 6e387aadffce..4f16d9c88350 100644
--- a/net/llc/llc_core.c
+++ b/net/llc/llc_core.c
@@ -135,22 +135,15 @@ static struct packet_type llc_packet_type __read_mostly = {
.func = llc_rcv,
};
-static struct packet_type llc_tr_packet_type __read_mostly = {
- .type = cpu_to_be16(ETH_P_TR_802_2),
- .func = llc_rcv,
-};
-
static int __init llc_init(void)
{
dev_add_pack(&llc_packet_type);
- dev_add_pack(&llc_tr_packet_type);
return 0;
}
static void __exit llc_exit(void)
{
dev_remove_pack(&llc_packet_type);
- dev_remove_pack(&llc_tr_packet_type);
}
module_init(llc_init);
--
2.30.2
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