[syzbot] [mptcp?] KMSAN: uninit-value in mptcp_incoming_options

[syzbot] [mptcp?] KMSAN: uninit-value in mptcp_incoming_options

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c2d5304e6c64 Merge tag 'platform-drivers-x86-v6.7-2' of gi..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1536e3d4e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e32016b84cf917ca
dashboard link: https://syzkaller.appspot.com/bug?extid=b834a6b2decad004cfa1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11469724e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13934aaf680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/23ea827adf3b/disk-c2d5304e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0f964ac588f5/vmlinux-c2d5304e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b061be889285/bzImage-c2d5304e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in mptcp_incoming_options+0xc93/0x3a80 net/mptcp/options.c:1197
 mptcp_incoming_options+0xc93/0x3a80 net/mptcp/options.c:1197
 tcp_data_queue+0xb4/0x7f20 net/ipv4/tcp_input.c:5141
 tcp_rcv_established+0x1132/0x2600 net/ipv4/tcp_input.c:6155
 tcp_v4_do_rcv+0x8a8/0xff0 net/ipv4/tcp_ipv4.c:1906
 tcp_v4_rcv+0x4ce0/0x51a0 net/ipv4/tcp_ipv4.c:2329
 ip_protocol_deliver_rcu+0x264/0x1300 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x2b8/0x440 net/ipv4/ip_input.c:233
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:461 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:449 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip_rcv+0x476/0x770 net/ipv4/ip_input.c:569
 __netif_receive_skb_one_core net/core/dev.c:5529 [inline]
 __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5643
 process_backlog+0x480/0x8b0 net/core/dev.c:5971
 __napi_poll+0xe3/0x970 net/core/dev.c:6533
 napi_poll net/core/dev.c:6602 [inline]
 net_rx_action+0x884/0x16d0 net/core/dev.c:6735
 __do_softirq+0x1b7/0x7c3 kernel/softirq.c:553
 do_softirq+0x9a/0xf0 kernel/softirq.c:454
 __local_bh_enable_ip+0x99/0xa0 kernel/softirq.c:381
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:817 [inline]
 __dev_queue_xmit+0x24ff/0x5130 net/core/dev.c:4373
 dev_queue_xmit include/linux/netdevice.h:3112 [inline]
 neigh_hh_output include/net/neighbour.h:526 [inline]
 neigh_output include/net/neighbour.h:540 [inline]
 ip_finish_output2+0x14be/0x1b40 net/ipv4/ip_output.c:235
 __ip_finish_output+0x266/0x720
 ip_finish_output+0x4b/0x550 net/ipv4/ip_output.c:323
 NF_HOOK_COND include/linux/netfilter.h:303 [inline]
 ip_output+0x15f/0x3e0 net/ipv4/ip_output.c:433
 dst_output include/net/dst.h:451 [inline]
 ip_local_out net/ipv4/ip_output.c:129 [inline]
 __ip_queue_xmit+0x1c02/0x1e00 net/ipv4/ip_output.c:535
 ip_queue_xmit+0x60/0x80 net/ipv4/ip_output.c:549
 __tcp_transmit_skb+0x3b26/0x4c40 net/ipv4/tcp_output.c:1462
 tcp_transmit_skb net/ipv4/tcp_output.c:1480 [inline]
 tcp_write_xmit+0x3e0f/0x8940 net/ipv4/tcp_output.c:2792
 __tcp_push_pending_frames+0xc4/0x380 net/ipv4/tcp_output.c:2977
 tcp_push+0x755/0x7a0 net/ipv4/tcp.c:736
 mptcp_push_release net/mptcp/protocol.c:1489 [inline]
 __mptcp_push_pending+0x8bc/0xde0 net/mptcp/protocol.c:1624
 mptcp_sendmsg+0x1e90/0x2300 net/mptcp/protocol.c:1890
 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmmsg+0x3c4/0x950 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2750
 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

Uninit was stored to memory at:
 mptcp_parse_option net/mptcp/options.c:110 [inline]
 mptcp_get_options+0x2d86/0x2e60 net/mptcp/options.c:396
 mptcp_incoming_options+0x124/0x3a80 net/mptcp/options.c:1139
 tcp_data_queue+0xb4/0x7f20 net/ipv4/tcp_input.c:5141
 tcp_rcv_established+0x1132/0x2600 net/ipv4/tcp_input.c:6155
 tcp_v4_do_rcv+0x8a8/0xff0 net/ipv4/tcp_ipv4.c:1906
 tcp_v4_rcv+0x4ce0/0x51a0 net/ipv4/tcp_ipv4.c:2329
 ip_protocol_deliver_rcu+0x264/0x1300 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x2b8/0x440 net/ipv4/ip_input.c:233
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:461 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:449 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip_rcv+0x476/0x770 net/ipv4/ip_input.c:569
 __netif_receive_skb_one_core net/core/dev.c:5529 [inline]
 __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5643
 process_backlog+0x480/0x8b0 net/core/dev.c:5971
 __napi_poll+0xe3/0x970 net/core/dev.c:6533
 napi_poll net/core/dev.c:6602 [inline]
 net_rx_action+0x884/0x16d0 net/core/dev.c:6735
 __do_softirq+0x1b7/0x7c3 kernel/softirq.c:553

Local variable mp_opt created at:
 mptcp_incoming_options+0x9b/0x3a80 net/mptcp/options.c:1116
 tcp_data_queue+0xb4/0x7f20 net/ipv4/tcp_input.c:5141

CPU: 0 PID: 5031 Comm: syz-executor376 Not tainted 6.7.0-rc2-syzkaller-00014-gc2d5304e6c64 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
=====================================================


---
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Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_incoming_options

[Kuniyuki Iwashima]

From: syzbot <syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com>
Date: Wed, 22 Nov 2023 07:43:23 -0800
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c2d5304e6c64 Merge tag 'platform-drivers-x86-v6.7-2' of gi..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1536e3d4e80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e32016b84cf917ca
> dashboard link: https://syzkaller.appspot.com/bug?extid=b834a6b2decad004cfa1
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11469724e80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13934aaf680000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/23ea827adf3b/disk-c2d5304e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/0f964ac588f5/vmlinux-c2d5304e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/b061be889285/bzImage-c2d5304e.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
> 
> =====================================================
> BUG: KMSAN: uninit-value in mptcp_incoming_options+0xc93/0x3a80 net/mptcp/options.c:1197

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c2d5304e6c648ebcf653bace7e51e0e6742e46c8

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index cd15ec73073e..01066aa7e67d 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -370,6 +370,7 @@ void mptcp_get_options(const struct sk_buff *skb,
 
 	/* initialize option status */
 	mp_opt->suboptions = 0;
+	mp_opt->use_ack = 0;
 
 	length = (th->doff * 4) - sizeof(struct tcphdr);
 	ptr = (const unsigned char *)(th + 1);

Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_incoming_options

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com

Tested on:

commit:         c2d5304e Merge tag 'platform-drivers-x86-v6.7-2' of gi..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16f3d6c8e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e32016b84cf917ca
dashboard link: https://syzkaller.appspot.com/bug?extid=b834a6b2decad004cfa1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=139ddc4f680000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_incoming_options

[Paolo Abeni]

Hi.

On Wed, 2023-11-22 at 16:48 -0800, Kuniyuki Iwashima wrote:
> From: syzbot <syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com>
> Date: Wed, 22 Nov 2023 07:43:23 -0800
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    c2d5304e6c64 Merge tag 'platform-drivers-x86-v6.7-2' of gi..
> > git tree:       upstream
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1536e3d4e80000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=e32016b84cf917ca
> > dashboard link: https://syzkaller.appspot.com/bug?extid=b834a6b2decad004cfa1
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11469724e80000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13934aaf680000
> > 
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/23ea827adf3b/disk-c2d5304e.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/0f964ac588f5/vmlinux-c2d5304e.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/b061be889285/bzImage-c2d5304e.xz
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
> > 
> > =====================================================
> > BUG: KMSAN: uninit-value in mptcp_incoming_options+0xc93/0x3a80 net/mptcp/options.c:1197
> 
> #syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c2d5304e6c648ebcf653bace7e51e0e6742e46c8
> 
> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> index cd15ec73073e..01066aa7e67d 100644
> --- a/net/mptcp/options.c
> +++ b/net/mptcp/options.c
> @@ -370,6 +370,7 @@ void mptcp_get_options(const struct sk_buff *skb,
>  
>  	/* initialize option status */
>  	mp_opt->suboptions = 0;
> +	mp_opt->use_ack = 0;
>  
>  	length = (th->doff * 4) - sizeof(struct tcphdr);
>  	ptr = (const unsigned char *)(th + 1);
> 

Thanks for the patch! AFAICS it should work, but I think the variant
proposed by Edward:

https://lore.kernel.org/netdev/tencent_B0E02F1D6C009450E8D6EC06CC6C7B5E6C0A@qq.com/

should be better, adding the additional instruction only in the code
path needing it. 

Thank!

Paolo

[PATCH] mptcp: fix uninit-value in mptcp_incoming_options

[Edward Adam Davis]

Added initialization use_ack to mptcp_parse_option().

Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 net/mptcp/options.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index cd15ec73073e..c53914012d01 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -108,6 +108,7 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 			mp_opt->suboptions |= OPTION_MPTCP_DSS;
 			mp_opt->use_map = 1;
 			mp_opt->mpc_map = 1;
+			mp_opt->use_ack = 0;
 			mp_opt->data_len = get_unaligned_be16(ptr);
 			ptr += 2;
 		}
-- 
2.25.1

Re: [PATCH] mptcp: fix uninit-value in mptcp_incoming_options

[Paolo Abeni]

On Thu, 2023-11-23 at 09:23 +0800, Edward Adam Davis wrote:
> Added initialization use_ack to mptcp_parse_option().
> 
> Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  net/mptcp/options.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> index cd15ec73073e..c53914012d01 100644
> --- a/net/mptcp/options.c
> +++ b/net/mptcp/options.c
> @@ -108,6 +108,7 @@ static void mptcp_parse_option(const struct sk_buff *skb,
>  			mp_opt->suboptions |= OPTION_MPTCP_DSS;
>  			mp_opt->use_map = 1;
>  			mp_opt->mpc_map = 1;
> +			mp_opt->use_ack = 0;
>  			mp_opt->data_len = get_unaligned_be16(ptr);
>  			ptr += 2;
>  		}

LGTM, and syzbot tested it.

Acked-by: Paolo Abeni <pabeni@redhat.com>

@Edward: for future similar patches, please add also the tested tag
from syzbot, will make tracking easier.

Thanks!

Paolo

Re: [PATCH] mptcp: fix uninit-value in mptcp_incoming_options

[Edward Adam Davis]

On Thu, 23 Nov 2023 17:41:31 +0100, Paolo Abeni wrote:
> > Added initialization use_ack to mptcp_parse_option().
> >
> > Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> >  net/mptcp/options.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> > index cd15ec73073e..c53914012d01 100644
> > --- a/net/mptcp/options.c
> > +++ b/net/mptcp/options.c
> > @@ -108,6 +108,7 @@ static void mptcp_parse_option(const struct sk_buff *skb,
> >  			mp_opt->suboptions |= OPTION_MPTCP_DSS;
> >  			mp_opt->use_map = 1;
> >  			mp_opt->mpc_map = 1;
> > +			mp_opt->use_ack = 0;
> >  			mp_opt->data_len = get_unaligned_be16(ptr);
> >  			ptr += 2;
> >  		}
> 
> LGTM, and syzbot tested it.
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> 
> @Edward: for future similar patches, please add also the tested tag
> from syzbot, will make tracking easier.
OK, I will.

Edward

Re: [PATCH] mptcp: fix uninit-value in mptcp_incoming_options

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu, 23 Nov 2023 09:23:39 +0800 you wrote:
> Added initialization use_ack to mptcp_parse_option().
> 
> Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  net/mptcp/options.c | 1 +
>  1 file changed, 1 insertion(+)

Here is the summary with links:
  - mptcp: fix uninit-value in mptcp_incoming_options
    https://git.kernel.org/netdev/net/c/237ff253f2d4

You are awesome, thank you!
-- 
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