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[PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()

Raghavendra Rao Ananta posted 1 patch 3 months, 1 week ago 
drivers/vfio/device_cdev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by Raghavendra Rao Ananta 3 months, 1 week ago 
For the cases where user includes a non-zero value in 'token_uuid_ptr'
field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
copy_struct_from_user() expects the newly introduced field to be zero-ed,
which would be incorrect in this case.

Fix this by passing the actual size of the kernel struct. If working
with a newer userspace, copy_struct_from_user() would copy the
'token_uuid_ptr' field, and if working with an old userspace, it would
zero out this field, thus still retaining backward compatibility.

Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
 drivers/vfio/device_cdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index 480cac3a0c274..8ceca24ac136c 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -99,7 +99,7 @@ long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
 		return ret;
 	if (user_size < minsz)
 		return -EINVAL;
-	ret = copy_struct_from_user(&bind, minsz, arg, user_size);
+	ret = copy_struct_from_user(&bind, sizeof(bind), arg, user_size);
 	if (ret)
 		return ret;
 

base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
-- 
2.51.1.930.gacf6e81ea2-goog
Re: [PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by liulongfang 3 months, 1 week ago 
On 2025/10/31 1:12, Raghavendra Rao Ananta wrote:
> For the cases where user includes a non-zero value in 'token_uuid_ptr'
> field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
> in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
> copy_struct_from_user() expects the newly introduced field to be zero-ed,
> which would be incorrect in this case.
> 
> Fix this by passing the actual size of the kernel struct. If working
> with a newer userspace, copy_struct_from_user() would copy the
> 'token_uuid_ptr' field, and if working with an old userspace, it would
> zero out this field, thus still retaining backward compatibility.
> 
> Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")

Hi Ananta,

This patch also has another bug: in the hisi_acc_vfio_pci.c driver, It have two "struct vfio_device_ops"
Only one of them, "hisi_acc_vfio_pci_ops" has match_token_uuid added,
while the other one, "hisi_acc_vfio_pci_migrn_ops", is missing it.
This will cause a QEMU crash (call trace) when QEMU tries to start the device.

Could you please help include this fix in your patchset as well?

--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -1637,6 +1637,7 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
 	.mmap = hisi_acc_vfio_pci_mmap,
 	.request = vfio_pci_core_request,
 	.match = vfio_pci_core_match,
+	.match_token_uuid = vfio_pci_core_match_token_uuid,
 	.bind_iommufd = vfio_iommufd_physical_bind,
 	.unbind_iommufd = vfio_iommufd_physical_unbind,
 	.attach_ioas = vfio_iommufd_physical_attach_ioas,

Thanks.
Longfang.

> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> ---
>  drivers/vfio/device_cdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index 480cac3a0c274..8ceca24ac136c 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -99,7 +99,7 @@ long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
>  		return ret;
>  	if (user_size < minsz)
>  		return -EINVAL;
> -	ret = copy_struct_from_user(&bind, minsz, arg, user_size);
> +	ret = copy_struct_from_user(&bind, sizeof(bind), arg, user_size);
>  	if (ret)
>  		return ret;
>  
> 
> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
>
Re: [PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by Raghavendra Rao Ananta 3 months, 1 week ago 
On Thu, Oct 30, 2025 at 6:34 PM liulongfang <liulongfang@huawei.com> wrote:
>
> On 2025/10/31 1:12, Raghavendra Rao Ananta wrote:
> > For the cases where user includes a non-zero value in 'token_uuid_ptr'
> > field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
> > in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
> > copy_struct_from_user() expects the newly introduced field to be zero-ed,
> > which would be incorrect in this case.
> >
> > Fix this by passing the actual size of the kernel struct. If working
> > with a newer userspace, copy_struct_from_user() would copy the
> > 'token_uuid_ptr' field, and if working with an old userspace, it would
> > zero out this field, thus still retaining backward compatibility.
> >
> > Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")
>
> Hi Ananta,
>
> This patch also has another bug: in the hisi_acc_vfio_pci.c driver, It have two "struct vfio_device_ops"
> Only one of them, "hisi_acc_vfio_pci_ops" has match_token_uuid added,
> while the other one, "hisi_acc_vfio_pci_migrn_ops", is missing it.
> This will cause a QEMU crash (call trace) when QEMU tries to start the device.
>
> Could you please help include this fix in your patchset as well?
>
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -1637,6 +1637,7 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
>         .mmap = hisi_acc_vfio_pci_mmap,
>         .request = vfio_pci_core_request,
>         .match = vfio_pci_core_match,
> +       .match_token_uuid = vfio_pci_core_match_token_uuid,
>         .bind_iommufd = vfio_iommufd_physical_bind,
>         .unbind_iommufd = vfio_iommufd_physical_unbind,
>         .attach_ioas = vfio_iommufd_physical_attach_ioas,
>
Sent as a separate patch in v2:
https://lore.kernel.org/all/20251031170603.2260022-3-rananta@google.com/
(untested).

Thank you.
Raghavendra
Re: [PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by liulongfang 3 months, 1 week ago 
On 2025/11/1 1:09, Raghavendra Rao Ananta wrote:
> On Thu, Oct 30, 2025 at 6:34 PM liulongfang <liulongfang@huawei.com> wrote:
>>
>> On 2025/10/31 1:12, Raghavendra Rao Ananta wrote:
>>> For the cases where user includes a non-zero value in 'token_uuid_ptr'
>>> field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
>>> in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
>>> copy_struct_from_user() expects the newly introduced field to be zero-ed,
>>> which would be incorrect in this case.
>>>
>>> Fix this by passing the actual size of the kernel struct. If working
>>> with a newer userspace, copy_struct_from_user() would copy the
>>> 'token_uuid_ptr' field, and if working with an old userspace, it would
>>> zero out this field, thus still retaining backward compatibility.
>>>
>>> Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")
>>
>> Hi Ananta,
>>
>> This patch also has another bug: in the hisi_acc_vfio_pci.c driver, It have two "struct vfio_device_ops"
>> Only one of them, "hisi_acc_vfio_pci_ops" has match_token_uuid added,
>> while the other one, "hisi_acc_vfio_pci_migrn_ops", is missing it.
>> This will cause a QEMU crash (call trace) when QEMU tries to start the device.
>>
>> Could you please help include this fix in your patchset as well?
>>
>> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>> @@ -1637,6 +1637,7 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
>>         .mmap = hisi_acc_vfio_pci_mmap,
>>         .request = vfio_pci_core_request,
>>         .match = vfio_pci_core_match,
>> +       .match_token_uuid = vfio_pci_core_match_token_uuid,
>>         .bind_iommufd = vfio_iommufd_physical_bind,
>>         .unbind_iommufd = vfio_iommufd_physical_unbind,
>>         .attach_ioas = vfio_iommufd_physical_attach_ioas,
>>
> Sent as a separate patch in v2:
> https://lore.kernel.org/all/20251031170603.2260022-3-rananta@google.com/
> (untested).
>

I've tested this patch locally, and after applying it, QEMU no longer fails to start
and the functionality works as expected.

Thanks.
Longfang.

> Thank you.
> Raghavendra
> .
>
Re: [PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by Jason Gunthorpe 3 months, 1 week ago 
On Thu, Oct 30, 2025 at 05:12:38PM +0000, Raghavendra Rao Ananta wrote:
> For the cases where user includes a non-zero value in 'token_uuid_ptr'
> field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
> in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
> copy_struct_from_user() expects the newly introduced field to be zero-ed,
> which would be incorrect in this case.
> 
> Fix this by passing the actual size of the kernel struct. If working
> with a newer userspace, copy_struct_from_user() would copy the
> 'token_uuid_ptr' field, and if working with an old userspace, it would
> zero out this field, thus still retaining backward compatibility.
> 
> Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> ---
>  drivers/vfio/device_cdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Cc: stable@vger.kernel.org
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Though I feel this was copied from some other spot in vfio so I wonder
if we have a larger set of things that are a little off..

Jason
Re: [PATCH] vfio: Fix ksize arg while copying user struct in vfio_df_ioctl_bind_iommufd()
Posted by Raghavendra Rao Ananta 3 months, 1 week ago 
On Thu, Oct 30, 2025 at 11:31 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Thu, Oct 30, 2025 at 05:12:38PM +0000, Raghavendra Rao Ananta wrote:
> > For the cases where user includes a non-zero value in 'token_uuid_ptr'
> > field of 'struct vfio_device_bind_iommufd', the copy_struct_from_user()
> > in vfio_df_ioctl_bind_iommufd() fails with -E2BIG. For the 'minsz' passed,
> > copy_struct_from_user() expects the newly introduced field to be zero-ed,
> > which would be incorrect in this case.
> >
> > Fix this by passing the actual size of the kernel struct. If working
> > with a newer userspace, copy_struct_from_user() would copy the
> > 'token_uuid_ptr' field, and if working with an old userspace, it would
> > zero out this field, thus still retaining backward compatibility.
> >
> > Fixes: 86624ba3b522 ("vfio/pci: Do vf_token checks for VFIO_DEVICE_BIND_IOMMUFD")
> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> > ---
> >  drivers/vfio/device_cdev.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Cc: stable@vger.kernel.org
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
>
> Though I feel this was copied from some other spot in vfio so I wonder
> if we have a larger set of things that are a little off..
>
I could only find vfio_df_ioctl_bind_iommufd() in vfio referencing
copy_struct_from_user(). The other closest would be in
drivers/iommu/iommufd/main.c::iommufd_fops_ioctl(), which seems to be
doing the right thing.

Thank you.
Raghavendra

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