linux-kernel - Re: [PATCH] vdpa/vp_vdpa: fix kfree a wrong pointer in vp_vdpa

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Date:   Thu, 8 Dec 2022 15:33:13 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cindy Lu <lulu@...hat.com>
Cc:     Nanyong Sun <sunnanyong@...wei.com>, mst@...hat.com,
        gautam.dawar@...inx.com, elic@...dia.com, sgarzare@...hat.com,
        wangrong68@...wei.com, virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, liushixin2@...wei.com,
        wangkefeng.wang@...wei.com
Subject: Re: [PATCH] vdpa/vp_vdpa: fix kfree a wrong pointer in vp_vdpa_remove

On Thu, Dec 8, 2022 at 10:05 AM Cindy Lu <lulu@...hat.com> wrote:
>
> On Wed, 7 Dec 2022 at 19:23, Nanyong Sun <sunnanyong@...wei.com> wrote:
> >
> > From: Rong Wang <wangrong68@...wei.com>
> >
> > In vp_vdpa_remove(), the code kfree(&vp_vdpa_mgtdev->mgtdev.id_table) uses
> > a reference of pointer as the argument of kfree, which is the wrong pointer
> > and then may hit crash like this:
> >
> > Unable to handle kernel paging request at virtual address 00ffff003363e30c
> > Internal error: Oops: 96000004 [#1] SMP
> > Call trace:
> >  rb_next+0x20/0x5c
> >  ext4_readdir+0x494/0x5c4 [ext4]
> >  iterate_dir+0x168/0x1b4
> >  __se_sys_getdents64+0x68/0x170
> >  __arm64_sys_getdents64+0x24/0x30
> >  el0_svc_common.constprop.0+0x7c/0x1bc
> >  do_el0_svc+0x2c/0x94
> >  el0_svc+0x20/0x30
> >  el0_sync_handler+0xb0/0xb4
> >  el0_sync+0x160/0x180
> > Code: 54000220 f9400441 b4000161 aa0103e0 (f9400821)
> > SMP: stopping secondary CPUs
> > Starting crashdump kernel...
> >
> > Fixes: ffbda8e9df10 ("vdpa/vp_vdpa : add vdpa tool support in vp_vdpa")
> > Signed-off-by: Rong Wang <wangrong68@...wei.com>
> > Signed-off-by: Nanyong Sun <sunnanyong@...wei.com>
> > ---
> >  drivers/vdpa/virtio_pci/vp_vdpa.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
> > index d448db0c4de3..8fe267ca3e76 100644
> > --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
> > +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
> > @@ -647,7 +647,7 @@ static void vp_vdpa_remove(struct pci_dev *pdev)
> >         mdev = vp_vdpa_mgtdev->mdev;
> >         vp_modern_remove(mdev);
> >         vdpa_mgmtdev_unregister(&vp_vdpa_mgtdev->mgtdev);
> > -       kfree(&vp_vdpa_mgtdev->mgtdev.id_table);
> > +       kfree(vp_vdpa_mgtdev->mgtdev.id_table);
> >         kfree(mdev);
> >         kfree(vp_vdpa_mgtdev);
> >  }
> > --
> > 2.25.1
> >
> Reviewed-by: Cindy Lu <lulu@...hat.com>

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks

>