* [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
@ 2021-04-23 5:40 Juergen Gross
2021-04-23 6:55 ` Luca Fancellu
2021-05-10 9:26 ` Juergen Gross
0 siblings, 2 replies; 6+ messages in thread
From: Juergen Gross @ 2021-04-23 5:40 UTC (permalink / raw)
To: xen-devel, linux-kernel
Cc: Juergen Gross, Boris Ostrovsky, Stefano Stabellini, stable,
Marek Marczykowski-Górecki
Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
introduced an error in gntdev_mmap(): in case the call of
mmu_interval_notifier_insert_locked() fails the exit path should not
call mmu_interval_notifier_remove(), as this might result in NULL
dereferences.
One reason for failure is e.g. a signal pending for the running
process.
Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
Cc: stable@vger.kernel.org
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/gntdev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f01d58c7a042..a3e7be96527d 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1017,8 +1017,10 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
err = mmu_interval_notifier_insert_locked(
&map->notifier, vma->vm_mm, vma->vm_start,
vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
- if (err)
+ if (err) {
+ map->vma = NULL;
goto out_unlock_put;
+ }
}
mutex_unlock(&priv->lock);
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
2021-04-23 5:40 [PATCH] xen/gntdev: fix gntdev_mmap() error exit path Juergen Gross
@ 2021-04-23 6:55 ` Luca Fancellu
2021-04-23 7:00 ` Juergen Gross
2021-05-10 9:26 ` Juergen Gross
1 sibling, 1 reply; 6+ messages in thread
From: Luca Fancellu @ 2021-04-23 6:55 UTC (permalink / raw)
To: Juergen Gross
Cc: xen-devel, linux-kernel, Boris Ostrovsky, Stefano Stabellini,
stable, Marek Marczykowski-Górecki
> On 23 Apr 2021, at 06:40, Juergen Gross <jgross@suse.com> wrote:
>
> Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> introduced an error in gntdev_mmap(): in case the call of
> mmu_interval_notifier_insert_locked() fails the exit path should not
> call mmu_interval_notifier_remove(), as this might result in NULL
> dereferences.
>
> One reason for failure is e.g. a signal pending for the running
> process.
>
> Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> Cc: stable@vger.kernel.org
> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> drivers/xen/gntdev.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index f01d58c7a042..a3e7be96527d 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -1017,8 +1017,10 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
> err = mmu_interval_notifier_insert_locked(
> &map->notifier, vma->vm_mm, vma->vm_start,
> vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
> - if (err)
> + if (err) {
> + map->vma = NULL;
> goto out_unlock_put;
> + }
> }
> mutex_unlock(&priv->lock);
>
> --
> 2.26.2
>
>
Hi Juergen,
I can see from the code that there is another path to out_unlock_put label some lines before:
[…]
vma->vm_private_data = map;
if (map->flags) {
if ((vma->vm_flags & VM_WRITE) &&
(map->flags & GNTMAP_readonly))
goto out_unlock_put;
} else {
map->flags = GNTMAP_host_map;
if (!(vma->vm_flags & VM_WRITE))
map->flags |= GNTMAP_readonly;
}
[…]
Can be the case that use_ptemod is != 0 also for that path?
Cheers,
Luca
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
2021-04-23 6:55 ` Luca Fancellu
@ 2021-04-23 7:00 ` Juergen Gross
2021-04-23 7:04 ` Luca Fancellu
0 siblings, 1 reply; 6+ messages in thread
From: Juergen Gross @ 2021-04-23 7:00 UTC (permalink / raw)
To: Luca Fancellu
Cc: xen-devel, linux-kernel, Boris Ostrovsky, Stefano Stabellini,
stable, Marek Marczykowski-Górecki
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On 23.04.21 08:55, Luca Fancellu wrote:
>
>
>> On 23 Apr 2021, at 06:40, Juergen Gross <jgross@suse.com> wrote:
>>
>> Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
>> introduced an error in gntdev_mmap(): in case the call of
>> mmu_interval_notifier_insert_locked() fails the exit path should not
>> call mmu_interval_notifier_remove(), as this might result in NULL
>> dereferences.
>>
>> One reason for failure is e.g. a signal pending for the running
>> process.
>>
>> Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
>> Cc: stable@vger.kernel.org
>> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
>> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> drivers/xen/gntdev.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
>> index f01d58c7a042..a3e7be96527d 100644
>> --- a/drivers/xen/gntdev.c
>> +++ b/drivers/xen/gntdev.c
>> @@ -1017,8 +1017,10 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
>> err = mmu_interval_notifier_insert_locked(
>> &map->notifier, vma->vm_mm, vma->vm_start,
>> vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
>> - if (err)
>> + if (err) {
>> + map->vma = NULL;
>> goto out_unlock_put;
>> + }
>> }
>> mutex_unlock(&priv->lock);
>>
>> --
>> 2.26.2
>>
>>
>
> Hi Juergen,
>
> I can see from the code that there is another path to out_unlock_put label some lines before:
>
> […]
> vma->vm_private_data = map;
> if (map->flags) {
> if ((vma->vm_flags & VM_WRITE) &&
> (map->flags & GNTMAP_readonly))
> goto out_unlock_put;
> } else {
> map->flags = GNTMAP_host_map;
> if (!(vma->vm_flags & VM_WRITE))
> map->flags |= GNTMAP_readonly;
> }
> […]
>
> Can be the case that use_ptemod is != 0 also for that path?
map->vma will be NULL in this case, so there will be no problem
resulting from that path.
Juergen
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
2021-04-23 7:00 ` Juergen Gross
@ 2021-04-23 7:04 ` Luca Fancellu
2021-05-08 0:41 ` Marek Marczykowski-Górecki
0 siblings, 1 reply; 6+ messages in thread
From: Luca Fancellu @ 2021-04-23 7:04 UTC (permalink / raw)
To: Juergen Gross
Cc: xen-devel, linux-kernel, Boris Ostrovsky, Stefano Stabellini,
stable, Marek Marczykowski-Górecki
> On 23 Apr 2021, at 08:00, Juergen Gross <jgross@suse.com> wrote:
>
> On 23.04.21 08:55, Luca Fancellu wrote:
>>> On 23 Apr 2021, at 06:40, Juergen Gross <jgross@suse.com> wrote:
>>>
>>> Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
>>> introduced an error in gntdev_mmap(): in case the call of
>>> mmu_interval_notifier_insert_locked() fails the exit path should not
>>> call mmu_interval_notifier_remove(), as this might result in NULL
>>> dereferences.
>>>
>>> One reason for failure is e.g. a signal pending for the running
>>> process.
>>>
>>> Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
>>> Cc: stable@vger.kernel.org
>>> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
>>> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>> ---
>>> drivers/xen/gntdev.c | 4 +++-
>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
>>> index f01d58c7a042..a3e7be96527d 100644
>>> --- a/drivers/xen/gntdev.c
>>> +++ b/drivers/xen/gntdev.c
>>> @@ -1017,8 +1017,10 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
>>> err = mmu_interval_notifier_insert_locked(
>>> &map->notifier, vma->vm_mm, vma->vm_start,
>>> vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
>>> - if (err)
>>> + if (err) {
>>> + map->vma = NULL;
>>> goto out_unlock_put;
>>> + }
>>> }
>>> mutex_unlock(&priv->lock);
>>>
>>> --
>>> 2.26.2
>>>
>>>
>> Hi Juergen,
>> I can see from the code that there is another path to out_unlock_put label some lines before:
>> […]
>> vma->vm_private_data = map;
>> if (map->flags) {
>> if ((vma->vm_flags & VM_WRITE) &&
>> (map->flags & GNTMAP_readonly))
>> goto out_unlock_put;
>> } else {
>> map->flags = GNTMAP_host_map;
>> if (!(vma->vm_flags & VM_WRITE))
>> map->flags |= GNTMAP_readonly;
>> }
>> […]
>> Can be the case that use_ptemod is != 0 also for that path?
>
> map->vma will be NULL in this case, so there will be no problem
> resulting from that path.
>
Right, thanks, seems good to me.
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Cheers,
Luca
>
> Juergen
> <OpenPGP_0xB0DE9DD628BF132F.asc>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
2021-04-23 7:04 ` Luca Fancellu
@ 2021-05-08 0:41 ` Marek Marczykowski-Górecki
0 siblings, 0 replies; 6+ messages in thread
From: Marek Marczykowski-Górecki @ 2021-05-08 0:41 UTC (permalink / raw)
To: Luca Fancellu
Cc: Juergen Gross, xen-devel, linux-kernel, Boris Ostrovsky,
Stefano Stabellini, stable
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On Fri, Apr 23, 2021 at 08:04:57AM +0100, Luca Fancellu wrote:
> > On 23 Apr 2021, at 08:00, Juergen Gross <jgross@suse.com> wrote:
> > On 23.04.21 08:55, Luca Fancellu wrote:
> >>> On 23 Apr 2021, at 06:40, Juergen Gross <jgross@suse.com> wrote:
> >>>
> >>> Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> >>> introduced an error in gntdev_mmap(): in case the call of
> >>> mmu_interval_notifier_insert_locked() fails the exit path should not
> >>> call mmu_interval_notifier_remove(), as this might result in NULL
> >>> dereferences.
> >>>
> >>> One reason for failure is e.g. a signal pending for the running
> >>> process.
> >>>
> >>> Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> >>> Cc: stable@vger.kernel.org
> >>> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> >>> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> >>> Signed-off-by: Juergen Gross <jgross@suse.com>
(...)
> Right, thanks, seems good to me.
>
> Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Can somebody ack this fix please?
--
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] xen/gntdev: fix gntdev_mmap() error exit path
2021-04-23 5:40 [PATCH] xen/gntdev: fix gntdev_mmap() error exit path Juergen Gross
2021-04-23 6:55 ` Luca Fancellu
@ 2021-05-10 9:26 ` Juergen Gross
1 sibling, 0 replies; 6+ messages in thread
From: Juergen Gross @ 2021-05-10 9:26 UTC (permalink / raw)
To: xen-devel, linux-kernel
Cc: Boris Ostrovsky, Stefano Stabellini, stable,
Marek Marczykowski-Górecki
[-- Attachment #1.1.1: Type: text/plain, Size: 785 bytes --]
On 23.04.21 07:40, Juergen Gross wrote:
> Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> introduced an error in gntdev_mmap(): in case the call of
> mmu_interval_notifier_insert_locked() fails the exit path should not
> call mmu_interval_notifier_remove(), as this might result in NULL
> dereferences.
>
> One reason for failure is e.g. a signal pending for the running
> process.
>
> Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
> Cc: stable@vger.kernel.org
> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Pushed to xen/tip.git for-linus-5.13b
Juergen
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-04-23 5:40 [PATCH] xen/gntdev: fix gntdev_mmap() error exit path Juergen Gross
2021-04-23 6:55 ` Luca Fancellu
2021-04-23 7:00 ` Juergen Gross
2021-04-23 7:04 ` Luca Fancellu
2021-05-08 0:41 ` Marek Marczykowski-Górecki
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