* [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure
@ 2016-01-29 14:43 Eric Auger
2016-01-29 21:41 ` Alex Williamson
0 siblings, 1 reply; 4+ messages in thread
From: Eric Auger @ 2016-01-29 14:43 UTC (permalink / raw)
To: linux-arm-kernel
In case vfio_msi_set_vector_signal fails we tear down everything.
In the tear down loop we compare int j against unsigned start. Given
the arithmetic conversion I think it is converted into an unsigned and
becomes 0xffffffff, leading to the loop being entered again and things
turn bad when accessing vdev->msix[vector].vector. So let's use int
parameters instead.
Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
drivers/vfio/pci/vfio_pci_intrs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 3b3ba15..510c48d 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -374,8 +374,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
return 0;
}
-static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
- unsigned count, int32_t *fds, bool msix)
+static int vfio_msi_set_block(struct vfio_pci_device *vdev, int start,
+ int count, int32_t *fds, bool msix)
{
int i, j, ret = 0;
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure
2016-01-29 14:43 [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure Eric Auger
@ 2016-01-29 21:41 ` Alex Williamson
2016-02-01 17:27 ` Eric Auger
0 siblings, 1 reply; 4+ messages in thread
From: Alex Williamson @ 2016-01-29 21:41 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, 2016-01-29 at 14:43 +0000, Eric Auger wrote:
> In case vfio_msi_set_vector_signal fails we tear down everything.
> In the tear down loop we compare int j against unsigned start. Given
> the arithmetic conversion I think it is converted into an unsigned and
> becomes 0xffffffff, leading to the loop being entered again and things
> turn bad when accessing vdev->msix[vector].vector. So let's use int
> parameters instead.
>?
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> ---
> ?drivers/vfio/pci/vfio_pci_intrs.c | 4 ++--
> ?1 file changed, 2 insertions(+), 2 deletions(-)
>?
> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> index 3b3ba15..510c48d 100644
> --- a/drivers/vfio/pci/vfio_pci_intrs.c
> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> @@ -374,8 +374,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> ? return 0;
> ?}
> ?
> -static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> - ??????unsigned count, int32_t *fds, bool msix)
> +static int vfio_msi_set_block(struct vfio_pci_device *vdev, int start,
> + ??????int count, int32_t *fds, bool msix)
> ?{
> ? int i, j, ret = 0;
> ?
Nice find, I don't think that's the only bug there though.??If @start is
-1 (UINT32_MAX) and @count is 1, then @j gets set to -1 in the setup and
we hit the same index dereference problem.??What if we did this instead:
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 3b3ba15..2ae84ad 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -309,14 +309,14 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
? ??????int vector, int fd, bool msix)
?{
? struct pci_dev *pdev = vdev->pdev;
- int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
- char *name = msix ? "vfio-msix" : "vfio-msi";
? struct eventfd_ctx *trigger;
- int ret;
+ int irq, ret;
?
- if (vector >= vdev->num_ctx)
+ if (vector < 0 || vector >= vdev->num_ctx)
? return -EINVAL;
?
+ irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
+
? if (vdev->ctx[vector].trigger) {
? free_irq(irq, vdev->ctx[vector].trigger);
? irq_bypass_unregister_producer(&vdev->ctx[vector].producer);
@@ -328,8 +328,9 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
? if (fd < 0)
? return 0;
?
- vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "%s[%d](%s)",
- ???name, vector, pci_name(pdev));
+ vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
+ ???msix ? "x" : "", vector,
+ ???pci_name(pdev));
? if (!vdev->ctx[vector].name)
? return -ENOMEM;
?
@@ -379,7 +380,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
?{
? int i, j, ret = 0;
?
- if (start + count > vdev->num_ctx)
+ if (start >= vdev->num_ctx || start + count > vdev->num_ctx)
? return -EINVAL;
?
? for (i = 0, j = start; i < count && !ret; i++, j++) {
@@ -388,7 +389,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
? }
?
? if (ret) {
- for (--j; j >= start; j--)
+ for (--j; j >= 0 && j >= start; j--)
? vfio_msi_set_vector_signal(vdev, j, -1, msix);
? }
?
So we fix the problem with vfio_msi_set_vector_signal() dereferencing
the array before it validates the index (even though it shouldn't be
able to get there anymore), and then we do a better job of verifying
start and count (comparing to num_ctx will use unsigned even though
num_ctx itself is signed) and finally explicitly test the <0 case, which
I suppose we could also do by casting start@that point (we know it's
within the bounds of a signed integer given the previous tests).
Thanks,
Alex
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure
2016-01-29 21:41 ` Alex Williamson
@ 2016-02-01 17:27 ` Eric Auger
2016-02-01 21:34 ` Alex Williamson
0 siblings, 1 reply; 4+ messages in thread
From: Eric Auger @ 2016-02-01 17:27 UTC (permalink / raw)
To: linux-arm-kernel
Hi Alex,
On 01/29/2016 10:41 PM, Alex Williamson wrote:
> On Fri, 2016-01-29 at 14:43 +0000, Eric Auger wrote:
>> In case vfio_msi_set_vector_signal fails we tear down everything.
>> In the tear down loop we compare int j against unsigned start. Given
>> the arithmetic conversion I think it is converted into an unsigned and
>> becomes 0xffffffff, leading to the loop being entered again and things
>> turn bad when accessing vdev->msix[vector].vector. So let's use int
>> parameters instead.
>>
>> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>> ---
>> drivers/vfio/pci/vfio_pci_intrs.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
>> index 3b3ba15..510c48d 100644
>> --- a/drivers/vfio/pci/vfio_pci_intrs.c
>> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
>> @@ -374,8 +374,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
>> return 0;
>> }
>>
>> -static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
>> - unsigned count, int32_t *fds, bool msix)
>> +static int vfio_msi_set_block(struct vfio_pci_device *vdev, int start,
>> + int count, int32_t *fds, bool msix)
>> {
>> int i, j, ret = 0;
>>
>
> Nice find, I don't think that's the only bug there though. If @start is
> -1 (UINT32_MAX) and @count is 1, then @j gets set to -1 in the setup and
> we hit the same index dereference problem. What if we did this instead:
>
> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> index 3b3ba15..2ae84ad 100644
> --- a/drivers/vfio/pci/vfio_pci_intrs.c
> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> @@ -309,14 +309,14 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> int vector, int fd, bool msix)
> {
> struct pci_dev *pdev = vdev->pdev;
> - int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
> - char *name = msix ? "vfio-msix" : "vfio-msi";
> struct eventfd_ctx *trigger;
> - int ret;
> + int irq, ret;
>
> - if (vector >= vdev->num_ctx)
> + if (vector < 0 || vector >= vdev->num_ctx)
> return -EINVAL;
>
> + irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
> +
> if (vdev->ctx[vector].trigger) {
> free_irq(irq, vdev->ctx[vector].trigger);
> irq_bypass_unregister_producer(&vdev->ctx[vector].producer);
> @@ -328,8 +328,9 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> if (fd < 0)
> return 0;
>
> - vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "%s[%d](%s)",
> - name, vector, pci_name(pdev));
> + vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
> + msix ? "x" : "", vector,
> + pci_name(pdev));
> if (!vdev->ctx[vector].name)
> return -ENOMEM;
>
> @@ -379,7 +380,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> {
> int i, j, ret = 0;
>
> - if (start + count > vdev->num_ctx)
> + if (start >= vdev->num_ctx || start + count > vdev->num_ctx)
> return -EINVAL;
>
> for (i = 0, j = start; i < count && !ret; i++, j++) {
> @@ -388,7 +389,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> }
>
> if (ret) {
> - for (--j; j >= start; j--)
> + for (--j; j >= 0 && j >= start; j--)
> vfio_msi_set_vector_signal(vdev, j, -1, msix);
> }
>
>
> So we fix the problem with vfio_msi_set_vector_signal() dereferencing
> the array before it validates the index (even though it shouldn't be
> able to get there anymore), and then we do a better job of verifying
> start and count (comparing to num_ctx will use unsigned even though
> num_ctx itself is signed) and finally explicitly test the <0 case, which
> I suppose we could also do by casting start at that point (we know it's
> within the bounds of a signed integer given the previous tests).
Yes it looks OK to me.
I guess you submit? I will test it.
Best Regards
Eric
> Thanks,
>
> Alex
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure
2016-02-01 17:27 ` Eric Auger
@ 2016-02-01 21:34 ` Alex Williamson
0 siblings, 0 replies; 4+ messages in thread
From: Alex Williamson @ 2016-02-01 21:34 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, 2016-02-01 at 18:27 +0100, Eric Auger wrote:
> Hi Alex,
> On 01/29/2016 10:41 PM, Alex Williamson wrote:
> > On Fri, 2016-01-29 at 14:43 +0000, Eric Auger wrote:
> > > In case vfio_msi_set_vector_signal fails we tear down everything.
> > > In the tear down loop we compare int j against unsigned start. Given
> > > the arithmetic conversion I think it is converted into an unsigned and
> > > becomes 0xffffffff, leading to the loop being entered again and things
> > > turn bad when accessing vdev->msix[vector].vector. So let's use int
> > > parameters instead.
> > > ?
> > > Signed-off-by: Eric Auger <eric.auger@linaro.org>
> > > ---
> > > ?drivers/vfio/pci/vfio_pci_intrs.c | 4 ++--
> > > ?1 file changed, 2 insertions(+), 2 deletions(-)
> > > ?
> > > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> > > index 3b3ba15..510c48d 100644
> > > --- a/drivers/vfio/pci/vfio_pci_intrs.c
> > > +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> > > @@ -374,8 +374,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> > > ? return 0;
> > > ?}
> > > ?
> > > -static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> > > - ??????unsigned count, int32_t *fds, bool msix)
> > > +static int vfio_msi_set_block(struct vfio_pci_device *vdev, int start,
> > > + ??????int count, int32_t *fds, bool msix)
> > > ?{
> > > ? int i, j, ret = 0;
> > > ?
> >?
> > Nice find, I don't think that's the only bug there though.??If @start is
> > -1 (UINT32_MAX) and @count is 1, then @j gets set to -1 in the setup and
> > we hit the same index dereference problem.??What if we did this instead:
> >?
> > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> > index 3b3ba15..2ae84ad 100644
> > --- a/drivers/vfio/pci/vfio_pci_intrs.c
> > +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> > @@ -309,14 +309,14 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> > ? ??????int vector, int fd, bool msix)
> > ?{
> > ? struct pci_dev *pdev = vdev->pdev;
> > - int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
> > - char *name = msix ? "vfio-msix" : "vfio-msi";
> > ? struct eventfd_ctx *trigger;
> > - int ret;
> > + int irq, ret;
> > ?
> > - if (vector >= vdev->num_ctx)
> > + if (vector < 0 || vector >= vdev->num_ctx)
> > ? return -EINVAL;
> > ?
> > + irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
> > +
> > ? if (vdev->ctx[vector].trigger) {
> > ? free_irq(irq, vdev->ctx[vector].trigger);
> > ? irq_bypass_unregister_producer(&vdev->ctx[vector].producer);
> > @@ -328,8 +328,9 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> > ? if (fd < 0)
> > ? return 0;
> > ?
> > - vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "%s[%d](%s)",
> > - ???name, vector, pci_name(pdev));
> > + vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
> > + ???msix ? "x" : "", vector,
> > + ???pci_name(pdev));
> > ? if (!vdev->ctx[vector].name)
> > ? return -ENOMEM;
> > ?
> > @@ -379,7 +380,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> > ?{
> > ? int i, j, ret = 0;
> > ?
> > - if (start + count > vdev->num_ctx)
> > + if (start >= vdev->num_ctx || start + count > vdev->num_ctx)
> > ? return -EINVAL;
> > ?
> > ? for (i = 0, j = start; i < count && !ret; i++, j++) {
> > @@ -388,7 +389,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
> > ? }
> > ?
> > ? if (ret) {
> > - for (--j; j >= start; j--)
> > + for (--j; j >= 0 && j >= start; j--)
> > ? vfio_msi_set_vector_signal(vdev, j, -1, msix);
> > ? }
> > ?
> >?
> > So we fix the problem with vfio_msi_set_vector_signal() dereferencing
> > the array before it validates the index (even though it shouldn't be
> > able to get there anymore), and then we do a better job of verifying
> > start and count (comparing to num_ctx will use unsigned even though
> > num_ctx itself is signed) and finally explicitly test the <0 case, which
> > I suppose we could also do by casting start at that point (we know it's
> > within the bounds of a signed integer given the previous tests).
>?
> Yes it looks OK to me.
>?
> I guess you submit? I will test it.
Yep, I'll post a real patch.??Thanks,
Alex
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-01-29 14:43 [PATCH] vfio: pci: fix oops in case of vfio_msi_set_vector_signal failure Eric Auger
2016-01-29 21:41 ` Alex Williamson
2016-02-01 17:27 ` Eric Auger
2016-02-01 21:34 ` Alex Williamson
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