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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni CC: Paul Gortmaker , Kuniyuki Iwashima , Kuniyuki Iwashima , , Subject: [PATCH v1 net] llc: Initialise addr before __llc_lookup(). Date: Thu, 18 Jan 2024 17:41:49 -0800 Message-ID: <20240119014149.60438-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D043UWA004.ant.amazon.com (10.13.139.41) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: Bulk 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)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={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@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b5ad66046b913bc04c6f Signed-off-by: Kuniyuki Iwashima --- 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