linux-kernel - Re: [PATCH] vduse: fix NULL pointer dereference

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Message-ID: <CACycT3t_Lea_g0T4sx8MR+r3ziNFyBOY5jozEmYFgOZ0eG8Kwg@mail.gmail.com>
Date:   Thu, 15 Jun 2023 15:25:14 +0800
From:   Yongji Xie <xieyongji@...edance.com>
To:     Maxime Coquelin <maxime.coquelin@...hat.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>, xuanzhuo@...ux.alibaba.com,
        Greg KH <gregkh@...uxfoundation.org>,
        Sheng Zhao <sheng.zhao@...edance.com>,
        Parav Pandit <parav@...dia.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vduse: fix NULL pointer dereference

On Wed, Jun 14, 2023 at 7:52 PM Maxime Coquelin
<maxime.coquelin@...hat.com> wrote:
>
> vduse_vdpa_set_vq_affinity callback can be called
> with NULL value as cpu_mask when deleting the vduse
> device.
>
> This patch clears virtqueue's IRQ affinity mask value
> instead of dereferencing NULL cpu_mask.
>
> [ 4760.952149] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [ 4760.959110] #PF: supervisor read access in kernel mode
> [ 4760.964247] #PF: error_code(0x0000) - not-present page
> [ 4760.969385] PGD 0 P4D 0
> [ 4760.971927] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 4760.976112] CPU: 13 PID: 2346 Comm: vdpa Not tainted 6.4.0-rc6+ #4
> [ 4760.982291] Hardware name: Dell Inc. PowerEdge R640/0W23H8, BIOS 2.8.1 06/26/2020
> [ 4760.989769] RIP: 0010:memcpy_orig+0xc5/0x130
> [ 4760.994049] Code: 16 f8 4c 89 07 4c 89 4f 08 4c 89 54 17 f0 4c 89 5c 17 f8 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 fa 08 72 1b <4c> 8b 06 4c 8b 4c 16 f8 4c 89 07 4c 89 4c 17 f8 c3 cc cc cc cc 66
> [ 4761.012793] RSP: 0018:ffffb1d565abb830 EFLAGS: 00010246
> [ 4761.018020] RAX: ffff9f4bf6b27898 RBX: ffff9f4be23969c0 RCX: ffff9f4bcadf6400
> [ 4761.025152] RDX: 0000000000000008 RSI: 0000000000000000 RDI: ffff9f4bf6b27898
> [ 4761.032286] RBP: 0000000000000000 R08: 0000000000000008 R09: 0000000000000000
> [ 4761.039416] R10: 0000000000000000 R11: 0000000000000600 R12: 0000000000000000
> [ 4761.046549] R13: 0000000000000000 R14: 0000000000000080 R15: ffffb1d565abbb10
> [ 4761.053680] FS:  00007f64c2ec2740(0000) GS:ffff9f635f980000(0000) knlGS:0000000000000000
> [ 4761.061765] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 4761.067513] CR2: 0000000000000000 CR3: 0000001875270006 CR4: 00000000007706e0
> [ 4761.074645] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 4761.081775] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 4761.088909] PKRU: 55555554
> [ 4761.091620] Call Trace:
> [ 4761.094074]  <TASK>
> [ 4761.096180]  ? __die+0x1f/0x70
> [ 4761.099238]  ? page_fault_oops+0x171/0x4f0
> [ 4761.103340]  ? exc_page_fault+0x7b/0x180
> [ 4761.107265]  ? asm_exc_page_fault+0x22/0x30
> [ 4761.111460]  ? memcpy_orig+0xc5/0x130
> [ 4761.115126]  vduse_vdpa_set_vq_affinity+0x3e/0x50 [vduse]
> [ 4761.120533]  virtnet_clean_affinity.part.0+0x3d/0x90 [virtio_net]
> [ 4761.126635]  remove_vq_common+0x1a4/0x250 [virtio_net]
> [ 4761.131781]  virtnet_remove+0x5d/0x70 [virtio_net]
> [ 4761.136580]  virtio_dev_remove+0x3a/0x90
> [ 4761.140509]  device_release_driver_internal+0x19b/0x200
> [ 4761.145742]  bus_remove_device+0xc2/0x130
> [ 4761.149755]  device_del+0x158/0x3e0
> [ 4761.153245]  ? kernfs_find_ns+0x35/0xc0
> [ 4761.157086]  device_unregister+0x13/0x60
> [ 4761.161010]  unregister_virtio_device+0x11/0x20
> [ 4761.165543]  device_release_driver_internal+0x19b/0x200
> [ 4761.170770]  bus_remove_device+0xc2/0x130
> [ 4761.174782]  device_del+0x158/0x3e0
> [ 4761.178276]  ? __pfx_vdpa_name_match+0x10/0x10 [vdpa]
> [ 4761.183336]  device_unregister+0x13/0x60
> [ 4761.187260]  vdpa_nl_cmd_dev_del_set_doit+0x63/0xe0 [vdpa]
>
> Fixes: 28f6288eb63d ("vduse: Support set_vq_affinity callback")
> Cc: xieyongji@...edance.com
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@...hat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 5f5c21674fdc..cdca94e85762 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -726,7 +726,11 @@ static int vduse_vdpa_set_vq_affinity(struct vdpa_device *vdpa, u16 idx,
>  {
>         struct vduse_dev *dev = vdpa_to_vduse(vdpa);
>
> -       cpumask_copy(&dev->vqs[idx]->irq_affinity, cpu_mask);
> +       if (cpu_mask)
> +               cpumask_copy(&dev->vqs[idx]->irq_affinity, cpu_mask);
> +       else
> +               cpumask_clear(&dev->vqs[idx]->irq_affinity);

I think we should set all the bits of irq affinity instead:
cpumask_setall(&dev->vqs[idx]->irq_affinity);

Thanks,
Yongji