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Date:   Fri, 27 Oct 2023 10:24:54 +0200
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     syzbot <syzbot+0c8ce1da0ac31abbadcd@syzkaller.appspotmail.com>
Cc:     davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, pabeni@redhat.com, stefanha@redhat.com,
        syzkaller-bugs@googlegroups.com,
        virtualization@lists.linux-foundation.org, syoshida@redhat.com
Subject: Re: [syzbot] [net?] KMSAN: uninit-value in virtio_transport_recv_pkt
Message-ID: <ooihytsfbk3brbwi2oj27ju3ff43ns36qhksfixrxdau2nieor@ervvukakvk4n>
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On Fri, Oct 27, 2023 at 01:11:24AM -0700, syzbot wrote:
>Hello,
>
>syzbot found the following issue on:
>
>HEAD commit:    d90b0276af8f Merge tag 'hardening-v6.6-rc3' of git://git.k..
>git tree:       upstream
>console+strace: https://syzkaller.appspot.com/x/log.txt?x=102c8b22680000
>kernel config:  https://syzkaller.appspot.com/x/.config?x=6f1a4029b69273f3
>dashboard link: https://syzkaller.appspot.com/bug?extid=0c8ce1da0ac31abbadcd
>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=101e58ec680000
>C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17f7adb6680000
>
>Downloadable assets:
>disk image: https://storage.googleapis.com/syzbot-assets/83ae10beee39/disk-d90b0276.raw.xz
>vmlinux: https://storage.googleapis.com/syzbot-assets/c231992300f6/vmlinux-d90b0276.xz
>kernel image: https://storage.googleapis.com/syzbot-assets/6377c9c2ea97/bzImage-d90b0276.xz
>
>IMPORTANT: if you fix the issue, please add the following tag to the commit:
>Reported-by: syzbot+0c8ce1da0ac31abbadcd@syzkaller.appspotmail.com
>
>=====================================================
>BUG: KMSAN: uninit-value in virtio_transport_recv_pkt+0x1c42/0x2580 net/vmw_vsock/virtio_transport_common.c:1421
> virtio_transport_recv_pkt+0x1c42/0x2580 net/vmw_vsock/virtio_transport_common.c:1421
> vsock_loopback_work+0x3e2/0x5d0 net/vmw_vsock/vsock_loopback.c:120
> process_one_work kernel/workqueue.c:2630 [inline]
> process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2703
> worker_thread+0xf45/0x1490 kernel/workqueue.c:2784
> kthread+0x3e8/0x540 kernel/kthread.c:388
> ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
>
>Uninit was stored to memory at:
> virtio_transport_space_update net/vmw_vsock/virtio_transport_common.c:1274 [inline]
> virtio_transport_recv_pkt+0x1ea4/0x2580 net/vmw_vsock/virtio_transport_common.c:1415
> vsock_loopback_work+0x3e2/0x5d0 net/vmw_vsock/vsock_loopback.c:120
> process_one_work kernel/workqueue.c:2630 [inline]
> process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2703
> worker_thread+0xf45/0x1490 kernel/workqueue.c:2784
> kthread+0x3e8/0x540 kernel/kthread.c:388
> ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
>
>Uninit was created at:
> slab_post_alloc_hook+0x12f/0xb70 mm/slab.h:767
> slab_alloc_node mm/slub.c:3478 [inline]
> kmem_cache_alloc_node+0x577/0xa80 mm/slub.c:3523
> kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:559
> __alloc_skb+0x318/0x740 net/core/skbuff.c:650
> alloc_skb include/linux/skbuff.h:1286 [inline]
> virtio_vsock_alloc_skb include/linux/virtio_vsock.h:66 [inline]
> virtio_transport_alloc_skb+0x8b/0x1170 net/vmw_vsock/virtio_transport_common.c:58
> virtio_transport_reset_no_sock net/vmw_vsock/virtio_transport_common.c:957 [inline]
> virtio_transport_recv_pkt+0x1531/0x2580 net/vmw_vsock/virtio_transport_common.c:1387
> vsock_loopback_work+0x3e2/0x5d0 net/vmw_vsock/vsock_loopback.c:120
> process_one_work kernel/workqueue.c:2630 [inline]
> process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2703
> worker_thread+0xf45/0x1490 kernel/workqueue.c:2784
> kthread+0x3e8/0x540 kernel/kthread.c:388
> ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
>
>CPU: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.6.0-rc2-syzkaller-00337-gd90b0276af8f #0
>Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
>Workqueue: vsock-loopback vsock_loopback_work
>=====================================================
>

Shigeru Yoshida already posted a patch here:

https://lore.kernel.org/netdev/20231026150154.3536433-1-syoshida@redhat.com/