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

[Stefano Garzarella]

On Fri, Oct 27, 2023 at 10:48:39AM +0200, Eric Dumazet wrote:
> On Fri, Oct 27, 2023 at 10:25 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> > >
> > >=====================================================
> > >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@xxxxxxxxxx/
>
> Sure thing, this is why I released this syzbot report from my queue.

Thanks for that ;-)

Stefano