Messages in this thread Patch in this message | | | From | Stefano Garzarella <> | Date | Mon, 21 Feb 2022 15:09:42 +0100 | Subject | Re: [syzbot] kernel BUG in vhost_get_vq_desc |
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#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ f71077a4d84b
Patch sent upstream: https://lore.kernel.org/virtualization/20220221114916.107045-1-sgarzare@redhat.com/T/#u
On Sun, Feb 20, 2022 at 3:11 AM syzbot <syzbot+3140b17cb44a7b174008@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot has tested the proposed patch and the reproducer did not trigger any issue: > > Reported-and-tested-by: syzbot+3140b17cb44a7b174008@syzkaller.appspotmail.com > > Tested on: > > commit: f71077a4 Merge tag 'mmc-v5.17-rc1-2' of git://git.kern.. > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ > kernel config: https://syzkaller.appspot.com/x/.config?x=a78b064590b9f912 > dashboard link: https://syzkaller.appspot.com/bug?extid=3140b17cb44a7b174008 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > patch: https://syzkaller.appspot.com/x/patch.diff?x=143dc0d4700000 > > Note: testing is done by a robot and is best-effort only. > From 4951112bf98d3e10d3e9557986e5ca5419ca738f Mon Sep 17 00:00:00 2001 From: Stefano Garzarella <sgarzare@redhat.com> Date: Mon, 21 Feb 2022 11:07:49 +0100 Subject: [PATCH] vhost/vsock: don't check owner in vhost_vsock_stop() while releasing
vhost_vsock_stop() calls vhost_dev_check_owner() to check the device ownership. It expects current->mm to be valid.
vhost_vsock_stop() is also called by vhost_vsock_dev_release() when the user has not done close(), so when we are in do_exit(). In this case current->mm is invalid and we're releasing the device, so we should clean it anyway.
Let's check the owner only when vhost_vsock_stop() is called by an ioctl.
Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Cc: stable@vger.kernel.org Reported-by: syzbot+1e3ea63db39f2b4440e0@syzkaller.appspotmail.com Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- drivers/vhost/vsock.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index d6ca1c7ad513..f00d2dfd72b7 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -629,16 +629,18 @@ static int vhost_vsock_start(struct vhost_vsock *vsock) return ret; } -static int vhost_vsock_stop(struct vhost_vsock *vsock) +static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner) { size_t i; int ret; mutex_lock(&vsock->dev.mutex); - ret = vhost_dev_check_owner(&vsock->dev); - if (ret) - goto err; + if (check_owner) { + ret = vhost_dev_check_owner(&vsock->dev); + if (ret) + goto err; + } for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) { struct vhost_virtqueue *vq = &vsock->vqs[i]; @@ -753,7 +755,7 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file) * inefficient. Room for improvement here. */ vsock_for_each_connected_socket(vhost_vsock_reset_orphans); - vhost_vsock_stop(vsock); + vhost_vsock_stop(vsock, false); vhost_vsock_flush(vsock); vhost_dev_stop(&vsock->dev); @@ -868,7 +870,7 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl, if (start) return vhost_vsock_start(vsock); else - return vhost_vsock_stop(vsock); + return vhost_vsock_stop(vsock, true); case VHOST_GET_FEATURES: features = VHOST_VSOCK_FEATURES; if (copy_to_user(argp, &features, sizeof(features))) -- 2.35.1
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