Re: [Nouveau] [PATCH] nouveau/gem: fix user-after-free in nouveau_gem_new

[Jeremy Cline <jcline@redhat.com>]

On Thu, May 13, 2021 at 07:37:40PM +0200, Karol Herbst wrote:
> On Thu, May 13, 2021 at 5:25 PM Jeremy Cline <jcline@redhat.com> wrote:
> >
> > On Tue, May 11, 2021 at 06:35:53PM +0200, Karol Herbst wrote:
> > > If ttm_bo_init fails it will already call ttm_bo_put, so we don't have to
> > > do it through nouveau_bo_ref.
> > >
> > > ==================================================================
> > > BUG: KFENCE: use-after-free write in ttm_bo_put+0x11/0x40 [ttm]
> > >
> > > Use-after-free write at 0x000000004dc4663c (in kfence-#44):
> > >  ttm_bo_put+0x11/0x40 [ttm]
> > >  nouveau_gem_new+0xc1/0xf0 [nouveau]
> > >  nouveau_gem_ioctl_new+0x53/0xf0 [nouveau]
> > >  drm_ioctl_kernel+0xb2/0x100 [drm]
> > >  drm_ioctl+0x215/0x390 [drm]
> > >  nouveau_drm_ioctl+0x55/0xa0 [nouveau]
> > >  __x64_sys_ioctl+0x83/0xb0
> > >  do_syscall_64+0x33/0x40
> > >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > >
> > > kfence-#44 [0x00000000c0593b31-0x000000002e74122b, size=792, cache=kmalloc-1k] allocated by task 2657:
> > >  nouveau_bo_alloc+0x63/0x4c0 [nouveau]
> > >  nouveau_gem_new+0x38/0xf0 [nouveau]
> > >  nouveau_gem_ioctl_new+0x53/0xf0 [nouveau]
> > >  drm_ioctl_kernel+0xb2/0x100 [drm]
> > >  drm_ioctl+0x215/0x390 [drm]
> > >  nouveau_drm_ioctl+0x55/0xa0 [nouveau]
> > >  __x64_sys_ioctl+0x83/0xb0
> > >  do_syscall_64+0x33/0x40
> > >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > >
> > > freed by task 2657:
> > >  ttm_bo_release+0x1cc/0x300 [ttm]
> > >  ttm_bo_init_reserved+0x2ec/0x300 [ttm]
> > >  ttm_bo_init+0x5e/0xd0 [ttm]
> > >  nouveau_bo_init+0xaf/0xc0 [nouveau]
> > >  nouveau_gem_new+0x7f/0xf0 [nouveau]
> > >  nouveau_gem_ioctl_new+0x53/0xf0 [nouveau]
> > >  drm_ioctl_kernel+0xb2/0x100 [drm]
> > >  drm_ioctl+0x215/0x390 [drm]
> > >  nouveau_drm_ioctl+0x55/0xa0 [nouveau]
> > >  __x64_sys_ioctl+0x83/0xb0
> > >  do_syscall_64+0x33/0x40
> > >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > >
> > > Fixes: 019cbd4a4feb3 "drm/nouveau: Initialize GEM object before TTM object"
> > > Cc: Thierry Reding <treding@nvidia.com>
> > > Signed-off-by: Karol Herbst <kherbst@redhat.com>
> > > ---
> > >  drivers/gpu/drm/nouveau/nouveau_gem.c | 1 -
> > >  1 file changed, 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > > index c88cbb85f101..1165ff990fb5 100644
> > > --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> > > +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > > @@ -212,7 +212,6 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int align, uint32_t domain,
> > >
> > >       ret = nouveau_bo_init(nvbo, size, align, domain, NULL, NULL);
> > >       if (ret) {
> > > -             nouveau_bo_ref(NULL, &nvbo);
> > >               return ret;
> > >       }
> > >
> >
> > I submitted a patch for this in the beginning of December, it got
> > reviewed and it's languished ever since[0]. It's frustrating that these
> > issues have to get fixed multiple times by multiple developers because
> > bug fixes (with reviews!) aren't being accepted.
> >
> > [0] https://lists.freedesktop.org/archives/nouveau/2020-December/037571.html
> >
> > Anyway, for whatever it's worth:
> >
> > Reviewed-by: Jeremy Cline <jcline@redhat.com>
> >
> 
> oh indeed... as the patches are equivalent I'd say we should merge
> yours and add my
> 
> Reviewed-by: Karol Herbst <kherbst@redhat.com>
> 
> let's see if we can get it in this time *sigh*
> 

To be clear I don't care about the credit, accepting this patch is fine,
but I wanted to highlight how multiple developers are doing the same
work over and over because it seems nigh on impossible to get nouveau
kernel patches accepted.

- Jeremy

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