Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Thorsten Leemhuis]

On 23.03.2017 17:41, Michael S. Tsirkin wrote:
> On Thu, Mar 23, 2017 at 03:19:07PM +, Richard W.M. Jones wrote:
>> On Thu, Mar 23, 2017 at 01:13:50PM +0800, Jason Wang wrote:
>>> >From 312859b596e83a2164a8430343d31fce2a5ad808 Mon Sep 17 00:00:00 2001
>>> From: Jason Wang 
>>> Date: Thu, 23 Mar 2017 13:07:16 +0800
>>> Subject: [PATCH] virtio_pci: fix out of bound access for msix_names
>>> Signed-off-by: Jason Wang 
>> I tested this, and it does appear to fix the crashes in
>> vp_modern_find_vqs.  Therefore:
>> Tested-by: Richard W.M. Jones 
> I've queued the fix, thanks everyone!

Thx. Feel free to add

Tested-by: Thorsten Leemhuis 

as a kernel with that patch works well in my reboot tests so far.
 Ciao, Thorsten
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Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Michael S. Tsirkin]

On Thu, Mar 23, 2017 at 03:19:07PM +, Richard W.M. Jones wrote:
> On Thu, Mar 23, 2017 at 01:13:50PM +0800, Jason Wang wrote:
> > >From 312859b596e83a2164a8430343d31fce2a5ad808 Mon Sep 17 00:00:00 2001
> > From: Jason Wang 
> > Date: Thu, 23 Mar 2017 13:07:16 +0800
> > Subject: [PATCH] virtio_pci: fix out of bound access for msix_names
> > 
> > Signed-off-by: Jason Wang 
> 
> I tested this, and it does appear to fix the crashes in
> vp_modern_find_vqs.  Therefore:
> 
> Tested-by: Richard W.M. Jones 
> 
> Thanks,
> 
> Rich.

I've queued the fix, thanks everyone!

> >  drivers/virtio/virtio_pci_common.c | 9 +
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/virtio/virtio_pci_common.c 
> > b/drivers/virtio/virtio_pci_common.c
> > index df548a6..5905349 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -147,7 +147,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, 
> > unsigned nvqs,
> >  {
> > struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > const char *name = dev_name(_dev->vdev.dev);
> > -   int i, err = -ENOMEM, allocated_vectors, nvectors;
> > +   int i, j, err = -ENOMEM, allocated_vectors, nvectors;
> > unsigned flags = PCI_IRQ_MSIX;
> > bool shared = false;
> > u16 msix_vec;
> > @@ -212,7 +212,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, 
> > unsigned nvqs,
> > if (!vp_dev->msix_vector_map)
> > goto out_disable_config_irq;
> >  
> > -   allocated_vectors = 1; /* vector 0 is the config interrupt */
> > +   allocated_vectors = j = 1; /* vector 0 is the config interrupt */
> > for (i = 0; i < nvqs; ++i) {
> > if (!names[i]) {
> > vqs[i] = NULL;
> > @@ -236,18 +236,19 @@ static int vp_find_vqs_msix(struct virtio_device 
> > *vdev, unsigned nvqs,
> > continue;
> > }
> >  
> > -   snprintf(vp_dev->msix_names[i + 1],
> > +   snprintf(vp_dev->msix_names[j],
> >  sizeof(*vp_dev->msix_names), "%s-%s",
> >  dev_name(_dev->vdev.dev), names[i]);
> > err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
> >   vring_interrupt, IRQF_SHARED,
> > - vp_dev->msix_names[i + 1], vqs[i]);
> > + vp_dev->msix_names[j], vqs[i]);
> > if (err) {
> > /* don't free this irq on error */
> > vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;
> > goto out_remove_vqs;
> > }
> > vp_dev->msix_vector_map[i] = msix_vec;
> > +   j++;
> >  
> > /*
> >  * Use a different vector for each queue if they are available,
> > -- 
> > 2.7.4
> > 
> 
> 
> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-builder quickly builds VMs from scratch
> http://libguestfs.org/virt-builder.1.html
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Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Richard W.M. Jones]

On Thu, Mar 23, 2017 at 01:13:50PM +0800, Jason Wang wrote:
> >From 312859b596e83a2164a8430343d31fce2a5ad808 Mon Sep 17 00:00:00 2001
> From: Jason Wang 
> Date: Thu, 23 Mar 2017 13:07:16 +0800
> Subject: [PATCH] virtio_pci: fix out of bound access for msix_names
> 
> Signed-off-by: Jason Wang 

I tested this, and it does appear to fix the crashes in
vp_modern_find_vqs.  Therefore:

Tested-by: Richard W.M. Jones 

Thanks,

Rich.

>  drivers/virtio/virtio_pci_common.c | 9 +
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_pci_common.c 
> b/drivers/virtio/virtio_pci_common.c
> index df548a6..5905349 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -147,7 +147,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, 
> unsigned nvqs,
>  {
>   struct virtio_pci_device *vp_dev = to_vp_device(vdev);
>   const char *name = dev_name(_dev->vdev.dev);
> - int i, err = -ENOMEM, allocated_vectors, nvectors;
> + int i, j, err = -ENOMEM, allocated_vectors, nvectors;
>   unsigned flags = PCI_IRQ_MSIX;
>   bool shared = false;
>   u16 msix_vec;
> @@ -212,7 +212,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, 
> unsigned nvqs,
>   if (!vp_dev->msix_vector_map)
>   goto out_disable_config_irq;
>  
> - allocated_vectors = 1; /* vector 0 is the config interrupt */
> + allocated_vectors = j = 1; /* vector 0 is the config interrupt */
>   for (i = 0; i < nvqs; ++i) {
>   if (!names[i]) {
>   vqs[i] = NULL;
> @@ -236,18 +236,19 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, 
> unsigned nvqs,
>   continue;
>   }
>  
> - snprintf(vp_dev->msix_names[i + 1],
> + snprintf(vp_dev->msix_names[j],
>sizeof(*vp_dev->msix_names), "%s-%s",
>dev_name(_dev->vdev.dev), names[i]);
>   err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
> vring_interrupt, IRQF_SHARED,
> -   vp_dev->msix_names[i + 1], vqs[i]);
> +   vp_dev->msix_names[j], vqs[i]);
>   if (err) {
>   /* don't free this irq on error */
>   vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;
>   goto out_remove_vqs;
>   }
>   vp_dev->msix_vector_map[i] = msix_vec;
> + j++;
>  
>   /*
>* Use a different vector for each queue if they are available,
> -- 
> 2.7.4
> 


-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Christoph Hellwig]

On Thu, Mar 23, 2017 at 01:13:50PM +0800, Jason Wang wrote:
>
>
> On 2017年03月23日 08:30, Laura Abbott wrote:
>> Hi,
>>
>> Fedora has received multiple reports of crashes when running
>> 4.11 as a guest
>>
>> https://bugzilla.redhat.com/show_bug.cgi?id=1430297
>> https://bugzilla.redhat.com/show_bug.cgi?id=1434462
>> https://bugzilla.kernel.org/show_bug.cgi?id=194911
>> https://bugzilla.redhat.com/show_bug.cgi?id=1433899
>>
>> The crashes are not always consistent but they are generally
>> some flavor of oops or GPF in virtio related code. Multiple people
>> have done bisections (Thank you Thorsten Leemhuis and
>> Richard W.M. Jones) and found this commit to be at fault
>>
>> 07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507 is the first bad commit
>> commit 07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507
>> Author: Christoph Hellwig 
>> Date:   Sun Feb 5 18:15:19 2017 +0100
>>
>>  virtio_pci: use shared interrupts for virtqueues
>>   This lets IRQ layer handle dispatching IRQs to separate handlers 
>> for the
>>  case where we don't have per-VQ MSI-X vectors, and allows us to greatly
>>  simplify the code based on the assumption that we always have interrupt
>>  vector 0 (legacy INTx or config interrupt for MSI-X) available, and
>>  any other interrupt is request/freed throught the VQ, even if the
>>  actual interrupt line might be shared in some cases.
>>   This allows removing a great deal of variables keeping track of 
>> the
>>  interrupt state in struct virtio_pci_device, as we can now simply walk 
>> the
>>  list of VQs and deal with per-VQ interrupt handlers there, and only 
>> treat
>>  vector 0 special.
>>   Additionally clean up the VQ allocation code to properly unwind 
>> on error
>>  instead of having a single global cleanup label, which is error prone,
>>  and in this case also leads to more code.
>>   Signed-off-by: Christoph Hellwig 
>>  Signed-off-by: Michael S. Tsirkin 
>>
>> :04 04 79a8267ffb73f9d244267c5f68365305bddd4696 
>> 8832a160b978710bbd24ba6966f462b3faa27fcc M   drivers
>>
>> It doesn't revert cleanly so we haven't been able to do a clean
>> test. Any ideas?
>>
>> Thanks,
>> Laura
>
> Hello:
>
> Can you try the attached patch to see if it solves the problem? (At least 
> it silent KASan warnings for me).

This looks like a correct fix to me, independent of fixing the original
bug or not:

Reviewed-by: Christoph Hellwig 
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Re: [REGRESSION] 07ec51480b5e ("virtio_pci: use shared interrupts for virtqueues") causes crashes in guest

[Jason Wang]

On 2017年03月23日 08:30, Laura Abbott wrote:

Hi,

Fedora has received multiple reports of crashes when running
4.11 as a guest

https://bugzilla.redhat.com/show_bug.cgi?id=1430297
https://bugzilla.redhat.com/show_bug.cgi?id=1434462
https://bugzilla.kernel.org/show_bug.cgi?id=194911
https://bugzilla.redhat.com/show_bug.cgi?id=1433899

The crashes are not always consistent but they are generally
some flavor of oops or GPF in virtio related code. Multiple people
have done bisections (Thank you Thorsten Leemhuis and
Richard W.M. Jones) and found this commit to be at fault

07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507 is the first bad commit
commit 07ec51480b5eb1233f8c1b0f5d7a7c8d1247c507
Author: Christoph Hellwig 
Date:   Sun Feb 5 18:15:19 2017 +0100

 virtio_pci: use shared interrupts for virtqueues
 
 This lets IRQ layer handle dispatching IRQs to separate handlers for the

 case where we don't have per-VQ MSI-X vectors, and allows us to greatly
 simplify the code based on the assumption that we always have interrupt
 vector 0 (legacy INTx or config interrupt for MSI-X) available, and
 any other interrupt is request/freed throught the VQ, even if the
 actual interrupt line might be shared in some cases.
 
 This allows removing a great deal of variables keeping track of the

 interrupt state in struct virtio_pci_device, as we can now simply walk the
 list of VQs and deal with per-VQ interrupt handlers there, and only treat
 vector 0 special.
 
 Additionally clean up the VQ allocation code to properly unwind on error

 instead of having a single global cleanup label, which is error prone,
 and in this case also leads to more code.
 
 Signed-off-by: Christoph Hellwig 

 Signed-off-by: Michael S. Tsirkin 

:04 04 79a8267ffb73f9d244267c5f68365305bddd4696 
8832a160b978710bbd24ba6966f462b3faa27fcc M  drivers

It doesn't revert cleanly so we haven't been able to do a clean
test. Any ideas?

Thanks,
Laura


Hello:

Can you try the attached patch to see if it solves the problem? (At 
least it silent KASan warnings for me).


Thanks


>From 312859b596e83a2164a8430343d31fce2a5ad808 Mon Sep 17 00:00:00 2001
From: Jason Wang 
Date: Thu, 23 Mar 2017 13:07:16 +0800
Subject: [PATCH] virtio_pci: fix out of bound access for msix_names

Signed-off-by: Jason Wang 
---
 drivers/virtio/virtio_pci_common.c | 9 +
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index df548a6..5905349 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -147,7 +147,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	const char *name = dev_name(_dev->vdev.dev);
-	int i, err = -ENOMEM, allocated_vectors, nvectors;
+	int i, j, err = -ENOMEM, allocated_vectors, nvectors;
 	unsigned flags = PCI_IRQ_MSIX;
 	bool shared = false;
 	u16 msix_vec;
@@ -212,7 +212,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
 	if (!vp_dev->msix_vector_map)
 		goto out_disable_config_irq;
 
-	allocated_vectors = 1; /* vector 0 is the config interrupt */
+	allocated_vectors = j = 1; /* vector 0 is the config interrupt */
 	for (i = 0; i < nvqs; ++i) {
 		if (!names[i]) {
 			vqs[i] = NULL;
@@ -236,18 +236,19 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
 			continue;
 		}
 
-		snprintf(vp_dev->msix_names[i + 1],
+		snprintf(vp_dev->msix_names[j],
 			 sizeof(*vp_dev->msix_names), "%s-%s",
 			 dev_name(_dev->vdev.dev), names[i]);
 		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
   vring_interrupt, IRQF_SHARED,
-  vp_dev->msix_names[i + 1], vqs[i]);
+  vp_dev->msix_names[j], vqs[i]);
 		if (err) {
 			/* don't free this irq on error */
 			vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;
 			goto out_remove_vqs;
 		}
 		vp_dev->msix_vector_map[i] = msix_vec;
+		j++;
 
 		/*
 		 * Use a different vector for each queue if they are available,
-- 
2.7.4

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