Stefano Garzarella
2023-Oct-27 08:01 UTC
[PATCH net] virtio/vsock: Fix uninit-value in virtio_transport_recv_pkt()
On Fri, Oct 27, 2023 at 12:01:54AM +0900, Shigeru Yoshida wrote:>KMSAN reported the following uninit-value access issue: > >====================================================>BUG: KMSAN: uninit-value in virtio_transport_recv_pkt+0x1dfb/0x26a0 net/vmw_vsock/virtio_transport_common.c:1421 > virtio_transport_recv_pkt+0x1dfb/0x26a0 net/vmw_vsock/virtio_transport_common.c:1421 > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > process_one_work kernel/workqueue.c:2630 [inline] > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > kthread+0x3cc/0x520 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+0x1ee8/0x26a0 net/vmw_vsock/virtio_transport_common.c:1415 > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > process_one_work kernel/workqueue.c:2630 [inline] > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > kthread+0x3cc/0x520 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+0x105/0xad0 mm/slab.h:767 > slab_alloc_node mm/slub.c:3478 [inline] > kmem_cache_alloc_node+0x5a2/0xaf0 mm/slub.c:3523 > kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:559 > __alloc_skb+0x2fd/0x770 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+0x90/0x11e0 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+0x1279/0x26a0 net/vmw_vsock/virtio_transport_common.c:1387 > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > process_one_work kernel/workqueue.c:2630 [inline] > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > kthread+0x3cc/0x520 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: 1 PID: 10664 Comm: kworker/1:5 Not tainted 6.6.0-rc3-00146-g9f3ebbef746f #3 >Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 >Workqueue: vsock-loopback vsock_loopback_work >====================================================> >The following simple reproducer can cause the issue described above: > >int main(void) >{ > int sock; > struct sockaddr_vm addr = { > .svm_family = AF_VSOCK, > .svm_cid = VMADDR_CID_ANY, > .svm_port = 1234, > }; > > sock = socket(AF_VSOCK, SOCK_STREAM, 0); > connect(sock, (struct sockaddr *)&addr, sizeof(addr)); > return 0; >} > >This issue occurs because the `buf_alloc` and `fwd_cnt` fields of the >`struct virtio_vsock_hdr` are not initialized when a new skb is allocated >in `virtio_transport_alloc_skb()`. This patch resolves the issue by >initializing these fields during allocation. > >Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")CCin Bobby, the original author, for any additional comments/checks. Yeah, I see, before that commit we used kzalloc() to allocate the header so we forgot to reset these 2 fields, and checking they are the only 2 missing. I was thinking of putting a memset(hdr, 0, sizeof(*hdr)) in virtio_vsock_alloc_skb() but I think it's just extra unnecessary work, since here we set all the fields (thanks to this fix), in vhost/vsock.c we copy all the header we receive from the guest and in virtio_transport.c we already set it all to 0 because we are preallocating the receive buffers. So I'm fine with this fix!>Signed-off-by: Shigeru Yoshida <syoshida at redhat.com> >--- > net/vmw_vsock/virtio_transport_common.c | 2 ++ > 1 file changed, 2 insertions(+) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index 352d042b130b..102673bef189 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -68,6 +68,8 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info, > hdr->dst_port = cpu_to_le32(dst_port); > hdr->flags = cpu_to_le32(info->flags); > hdr->len = cpu_to_le32(len); >+ hdr->buf_alloc = cpu_to_le32(0); >+ hdr->fwd_cnt = cpu_to_le32(0); > > if (info->msg && len > 0) { > payload = skb_put(skb, len); >-- >2.41.0 >Reviewed-by: Stefano Garzarella <sgarzare at redhat.com> Thanks, Stefano
Stefano Garzarella
2023-Oct-27 08:18 UTC
[PATCH net] virtio/vsock: Fix uninit-value in virtio_transport_recv_pkt()
On Fri, Oct 27, 2023 at 10:01?AM Stefano Garzarella <sgarzare at redhat.com> wrote:> > On Fri, Oct 27, 2023 at 12:01:54AM +0900, Shigeru Yoshida wrote: > >KMSAN reported the following uninit-value access issue: > > > >====================================================> >BUG: KMSAN: uninit-value in virtio_transport_recv_pkt+0x1dfb/0x26a0 net/vmw_vsock/virtio_transport_common.c:1421 > > virtio_transport_recv_pkt+0x1dfb/0x26a0 net/vmw_vsock/virtio_transport_common.c:1421 > > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > > process_one_work kernel/workqueue.c:2630 [inline] > > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > > kthread+0x3cc/0x520 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+0x1ee8/0x26a0 net/vmw_vsock/virtio_transport_common.c:1415 > > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > > process_one_work kernel/workqueue.c:2630 [inline] > > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > > kthread+0x3cc/0x520 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+0x105/0xad0 mm/slab.h:767 > > slab_alloc_node mm/slub.c:3478 [inline] > > kmem_cache_alloc_node+0x5a2/0xaf0 mm/slub.c:3523 > > kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:559 > > __alloc_skb+0x2fd/0x770 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+0x90/0x11e0 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+0x1279/0x26a0 net/vmw_vsock/virtio_transport_common.c:1387 > > vsock_loopback_work+0x3bb/0x5a0 net/vmw_vsock/vsock_loopback.c:120 > > process_one_work kernel/workqueue.c:2630 [inline] > > process_scheduled_works+0xff6/0x1e60 kernel/workqueue.c:2703 > > worker_thread+0xeca/0x14d0 kernel/workqueue.c:2784 > > kthread+0x3cc/0x520 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: 1 PID: 10664 Comm: kworker/1:5 Not tainted 6.6.0-rc3-00146-g9f3ebbef746f #3 > >Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 > >Workqueue: vsock-loopback vsock_loopback_work > >====================================================> > > >The following simple reproducer can cause the issue described above: > > > >int main(void) > >{ > > int sock; > > struct sockaddr_vm addr = { > > .svm_family = AF_VSOCK, > > .svm_cid = VMADDR_CID_ANY, > > .svm_port = 1234, > > }; > > > > sock = socket(AF_VSOCK, SOCK_STREAM, 0); > > connect(sock, (struct sockaddr *)&addr, sizeof(addr)); > > return 0; > >} > > > >This issue occurs because the `buf_alloc` and `fwd_cnt` fields of the > >`struct virtio_vsock_hdr` are not initialized when a new skb is allocated > >in `virtio_transport_alloc_skb()`. This patch resolves the issue by > >initializing these fields during allocation. > > > >Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") > > CCin Bobby, the original author, for any additional comments/checks. > > Yeah, I see, before that commit we used kzalloc() to allocate the > header so we forgot to reset these 2 fields, and checking they are > the only 2 missing. > > I was thinking of putting a memset(hdr, 0, sizeof(*hdr)) in > virtio_vsock_alloc_skb() but I think it's just extra unnecessary work, > since here we set all the fields (thanks to this fix), in vhost/vsock.c > we copy all the header we receive from the guest and in > virtio_transport.c we already set it all to 0 because we are > preallocating the receive buffers. > > So I'm fine with this fix! > > >Signed-off-by: Shigeru Yoshida <syoshida at redhat.com> > >--- > > net/vmw_vsock/virtio_transport_common.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > >index 352d042b130b..102673bef189 100644 > >--- a/net/vmw_vsock/virtio_transport_common.c > >+++ b/net/vmw_vsock/virtio_transport_common.c > >@@ -68,6 +68,8 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info, > > hdr->dst_port = cpu_to_le32(dst_port); > > hdr->flags = cpu_to_le32(info->flags); > > hdr->len = cpu_to_le32(len); > >+ hdr->buf_alloc = cpu_to_le32(0); > >+ hdr->fwd_cnt = cpu_to_le32(0); > > > > if (info->msg && len > 0) { > > payload = skb_put(skb, len); > >-- > >2.41.0 > > > > Reviewed-by: Stefano Garzarella <sgarzare at redhat.com>syzbot just reported the same [1], should we add the following tag? Reported-by: syzbot+0c8ce1da0ac31abbadcd at syzkaller.appspotmail.com [1] https://lore.kernel.org/netdev/00000000000008b2940608ae3ce9 at google.com/ Thanks, Stefano