* [PATCH v2] virtio: pci: sanity check bar indexes
@ 2022-03-22 15:19 Keir Fraser
2022-03-23 7:57 ` Jason Wang
0 siblings, 1 reply; 7+ messages in thread
From: Keir Fraser @ 2022-03-22 15:19 UTC (permalink / raw)
To: Michael S. Tsirkin, Jason Wang
Cc: kernel-team, Keir Fraser, virtualization, linux-kernel
The bar index is used as an index into the device's resource list
and should be checked as within range for a standard bar.
Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
Signed-off-by: Keir Fraser <keirf@google.com>
---
drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index 5455bc041fb6..84bace98dff5 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
- u8 type, cap_len, id;
+ u8 type, cap_len, id, res_bar;
u32 tmp32;
u64 res_offset, res_length;
@@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
/* Type, and ID match, looks good */
pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
- bar), bar);
+ bar), &res_bar);
+ if (res_bar >= PCI_STD_NUM_BARS) {
+ dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
+ __func__, res_bar);
+ continue;
+ }
/* Read the lower 32bit of length and offset */
pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
@@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
length_hi), &tmp32);
res_length |= ((u64)tmp32) << 32;
+ *bar = res_bar;
*offset = res_offset;
*len = res_length;
diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
index e8b3ff2b9fbc..a6911d1e212a 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
&length);
+ if (bar >= PCI_STD_NUM_BARS) {
+ dev_err(&dev->dev,
+ "virtio_pci: bad capability bar %u\n", bar);
+ return NULL;
+ }
+
if (length <= start) {
dev_err(&dev->dev,
"virtio_pci: bad capability len %u (>%u expected)\n",
@@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
&bar);
/* Ignore structures with reserved BAR values */
- if (bar > 0x5)
+ if (bar >= PCI_STD_NUM_BARS)
continue;
if (type == cfg_type) {
--
2.35.1.894.gb6a874cedc-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-22 15:19 [PATCH v2] virtio: pci: sanity check bar indexes Keir Fraser
@ 2022-03-23 7:57 ` Jason Wang
2022-03-23 9:13 ` Keir Fraser
2022-03-23 12:01 ` Michael S. Tsirkin
0 siblings, 2 replies; 7+ messages in thread
From: Jason Wang @ 2022-03-23 7:57 UTC (permalink / raw)
To: Keir Fraser; +Cc: Michael S. Tsirkin, kernel-team, virtualization, linux-kernel
On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
>
> The bar index is used as an index into the device's resource list
> and should be checked as within range for a standard bar.
>
> Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
>
> Signed-off-by: Keir Fraser <keirf@google.com>
> ---
> drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> 2 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index 5455bc041fb6..84bace98dff5 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
>
> for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> - u8 type, cap_len, id;
> + u8 type, cap_len, id, res_bar;
> u32 tmp32;
> u64 res_offset, res_length;
>
> @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
>
> /* Type, and ID match, looks good */
> pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> - bar), bar);
> + bar), &res_bar);
> + if (res_bar >= PCI_STD_NUM_BARS) {
> + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> + __func__, res_bar);
> + continue;
> + }
>
> /* Read the lower 32bit of length and offset */
> pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
> @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> length_hi), &tmp32);
> res_length |= ((u64)tmp32) << 32;
>
> + *bar = res_bar;
> *offset = res_offset;
> *len = res_length;
>
> diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> index e8b3ff2b9fbc..a6911d1e212a 100644
> --- a/drivers/virtio/virtio_pci_modern_dev.c
> +++ b/drivers/virtio/virtio_pci_modern_dev.c
> @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> &length);
>
> + if (bar >= PCI_STD_NUM_BARS) {
> + dev_err(&dev->dev,
> + "virtio_pci: bad capability bar %u\n", bar);
> + return NULL;
> + }
> +
> if (length <= start) {
> dev_err(&dev->dev,
> "virtio_pci: bad capability len %u (>%u expected)\n",
> @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> &bar);
>
> /* Ignore structures with reserved BAR values */
> - if (bar > 0x5)
> + if (bar >= PCI_STD_NUM_BARS)
> continue;
Just notice that the spec said:
"
values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
the function located beginning at 10h in PCI Configuration Space and
used to map the structure into Memory or I/O Space. The BAR is
permitted to be either 32-bit or 64-bit, it can map Memory Space or
I/O Space.
Any other value is reserved for future use.
"
So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
this and other places.
Thanks
>
> if (type == cfg_type) {
> --
> 2.35.1.894.gb6a874cedc-goog
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-23 7:57 ` Jason Wang
@ 2022-03-23 9:13 ` Keir Fraser
2022-03-23 9:21 ` Jason Wang
2022-03-23 12:01 ` Michael S. Tsirkin
1 sibling, 1 reply; 7+ messages in thread
From: Keir Fraser @ 2022-03-23 9:13 UTC (permalink / raw)
To: Jason Wang; +Cc: Michael S. Tsirkin, kernel-team, virtualization, linux-kernel
On Wed, Mar 23, 2022 at 03:57:59PM +0800, Jason Wang wrote:
> On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
> >
> > The bar index is used as an index into the device's resource list
> > and should be checked as within range for a standard bar.
> >
> > Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
> >
> > Signed-off-by: Keir Fraser <keirf@google.com>
> > ---
> > drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> > drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> > 2 files changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index 5455bc041fb6..84bace98dff5 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> >
> > for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> > pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > - u8 type, cap_len, id;
> > + u8 type, cap_len, id, res_bar;
> > u32 tmp32;
> > u64 res_offset, res_length;
> >
> > @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> >
> > /* Type, and ID match, looks good */
> > pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > - bar), bar);
> > + bar), &res_bar);
> > + if (res_bar >= PCI_STD_NUM_BARS) {
> > + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> > + __func__, res_bar);
> > + continue;
> > + }
> >
> > /* Read the lower 32bit of length and offset */
> > pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
> > @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > length_hi), &tmp32);
> > res_length |= ((u64)tmp32) << 32;
> >
> > + *bar = res_bar;
> > *offset = res_offset;
> > *len = res_length;
> >
> > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > index e8b3ff2b9fbc..a6911d1e212a 100644
> > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> > pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > &length);
> >
> > + if (bar >= PCI_STD_NUM_BARS) {
> > + dev_err(&dev->dev,
> > + "virtio_pci: bad capability bar %u\n", bar);
> > + return NULL;
> > + }
> > +
> > if (length <= start) {
> > dev_err(&dev->dev,
> > "virtio_pci: bad capability len %u (>%u expected)\n",
> > @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> > &bar);
> >
> > /* Ignore structures with reserved BAR values */
> > - if (bar > 0x5)
> > + if (bar >= PCI_STD_NUM_BARS)
> > continue;
>
> Just notice that the spec said:
>
> "
> values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
> the function located beginning at 10h in PCI Configuration Space and
> used to map the structure into Memory or I/O Space. The BAR is
> permitted to be either 32-bit or 64-bit, it can map Memory Space or
> I/O Space.
>
> Any other value is reserved for future use.
> "
>
> So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
> this and other places.
The comparison(s) are changed to greater-or-equal, so they are logically
equivalent to the old check against naked 0x5 while documenting the intent
better.
> Thanks
>
> >
> > if (type == cfg_type) {
> > --
> > 2.35.1.894.gb6a874cedc-goog
> >
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-23 9:13 ` Keir Fraser
@ 2022-03-23 9:21 ` Jason Wang
0 siblings, 0 replies; 7+ messages in thread
From: Jason Wang @ 2022-03-23 9:21 UTC (permalink / raw)
To: Keir Fraser; +Cc: Michael S. Tsirkin, kernel-team, virtualization, linux-kernel
On Wed, Mar 23, 2022 at 5:13 PM Keir Fraser <keirf@google.com> wrote:
>
> On Wed, Mar 23, 2022 at 03:57:59PM +0800, Jason Wang wrote:
> > On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
> > >
> > > The bar index is used as an index into the device's resource list
> > > and should be checked as within range for a standard bar.
> > >
> > > Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
> > >
> > > Signed-off-by: Keir Fraser <keirf@google.com>
> > > ---
> > > drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> > > drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> > > 2 files changed, 15 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > > index 5455bc041fb6..84bace98dff5 100644
> > > --- a/drivers/virtio/virtio_pci_modern.c
> > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > >
> > > for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> > > pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > > - u8 type, cap_len, id;
> > > + u8 type, cap_len, id, res_bar;
> > > u32 tmp32;
> > > u64 res_offset, res_length;
> > >
> > > @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > >
> > > /* Type, and ID match, looks good */
> > > pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > > - bar), bar);
> > > + bar), &res_bar);
> > > + if (res_bar >= PCI_STD_NUM_BARS) {
> > > + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> > > + __func__, res_bar);
> > > + continue;
> > > + }
> > >
> > > /* Read the lower 32bit of length and offset */
> > > pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
> > > @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > > length_hi), &tmp32);
> > > res_length |= ((u64)tmp32) << 32;
> > >
> > > + *bar = res_bar;
> > > *offset = res_offset;
> > > *len = res_length;
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > > index e8b3ff2b9fbc..a6911d1e212a 100644
> > > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > > @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> > > pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > > &length);
> > >
> > > + if (bar >= PCI_STD_NUM_BARS) {
> > > + dev_err(&dev->dev,
> > > + "virtio_pci: bad capability bar %u\n", bar);
> > > + return NULL;
> > > + }
> > > +
> > > if (length <= start) {
> > > dev_err(&dev->dev,
> > > "virtio_pci: bad capability len %u (>%u expected)\n",
> > > @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> > > &bar);
> > >
> > > /* Ignore structures with reserved BAR values */
> > > - if (bar > 0x5)
> > > + if (bar >= PCI_STD_NUM_BARS)
> > > continue;
> >
> > Just notice that the spec said:
> >
> > "
> > values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
> > the function located beginning at 10h in PCI Configuration Space and
> > used to map the structure into Memory or I/O Space. The BAR is
> > permitted to be either 32-bit or 64-bit, it can map Memory Space or
> > I/O Space.
> >
> > Any other value is reserved for future use.
> > "
> >
> > So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
> > this and other places.
>
> The comparison(s) are changed to greater-or-equal, so they are logically
> equivalent to the old check against naked 0x5 while documenting the intent
> better.
You're right, So:
Acked-by: Jason Wang <jasowang@redhat.com>
>
> > Thanks
> >
> > >
> > > if (type == cfg_type) {
> > > --
> > > 2.35.1.894.gb6a874cedc-goog
> > >
> >
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-23 7:57 ` Jason Wang
2022-03-23 9:13 ` Keir Fraser
@ 2022-03-23 12:01 ` Michael S. Tsirkin
2022-03-23 13:21 ` Keir Fraser
1 sibling, 1 reply; 7+ messages in thread
From: Michael S. Tsirkin @ 2022-03-23 12:01 UTC (permalink / raw)
To: Jason Wang; +Cc: Keir Fraser, kernel-team, virtualization, linux-kernel
On Wed, Mar 23, 2022 at 03:57:59PM +0800, Jason Wang wrote:
> On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
> >
> > The bar index is used as an index into the device's resource list
> > and should be checked as within range for a standard bar.
> >
> > Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
> >
> > Signed-off-by: Keir Fraser <keirf@google.com>
> > ---
> > drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> > drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> > 2 files changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index 5455bc041fb6..84bace98dff5 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> >
> > for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> > pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > - u8 type, cap_len, id;
> > + u8 type, cap_len, id, res_bar;
> > u32 tmp32;
> > u64 res_offset, res_length;
> >
> > @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> >
> > /* Type, and ID match, looks good */
> > pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > - bar), bar);
> > + bar), &res_bar);
> > + if (res_bar >= PCI_STD_NUM_BARS) {
> > + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> > + __func__, res_bar);
> > + continue;
> > + }
> >
> > /* Read the lower 32bit of length and offset */
> > pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
In fact, the spec says such BAR values are reserved, not bad, so
the capabiluty should be ignored, they should not cause the driver to error out
or print errors.
> > @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > length_hi), &tmp32);
> > res_length |= ((u64)tmp32) << 32;
> >
> > + *bar = res_bar;
> > *offset = res_offset;
> > *len = res_length;
> >
> > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > index e8b3ff2b9fbc..a6911d1e212a 100644
> > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> > pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > &length);
> >
> > + if (bar >= PCI_STD_NUM_BARS) {
> > + dev_err(&dev->dev,
> > + "virtio_pci: bad capability bar %u\n", bar);
In fact, I would say the issue is less that bar is reserved.
The real issue is that the value apparently changed since
we read it the first time. I think it's a good idea to
reflect that in the message. Maybe find_capability should return
the capability structure so we don't need to re-read it from
the device?
> > + return NULL;
> > + }
> > +
> > if (length <= start) {
> > dev_err(&dev->dev,
> > "virtio_pci: bad capability len %u (>%u expected)\n",
> > @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> > &bar);
> >
> > /* Ignore structures with reserved BAR values */
> > - if (bar > 0x5)
> > + if (bar >= PCI_STD_NUM_BARS)
> > continue;
>
> Just notice that the spec said:
>
> "
> values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
> the function located beginning at 10h in PCI Configuration Space and
> used to map the structure into Memory or I/O Space. The BAR is
> permitted to be either 32-bit or 64-bit, it can map Memory Space or
> I/O Space.
>
> Any other value is reserved for future use.
> "
> So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
> this and other places.
>
> Thanks
It does not matter much IMHO, the reason spec uses 0 to 0x5 is precisely
because that's the standard number of BARs. Both ways work as long as we
are consistent, and I guess PCI_STD_NUM_BARS might be preferable since
people tend to copy paste values.
> >
> > if (type == cfg_type) {
> > --
> > 2.35.1.894.gb6a874cedc-goog
> >
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-23 12:01 ` Michael S. Tsirkin
@ 2022-03-23 13:21 ` Keir Fraser
2022-03-23 13:23 ` Michael S. Tsirkin
0 siblings, 1 reply; 7+ messages in thread
From: Keir Fraser @ 2022-03-23 13:21 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Jason Wang, kernel-team, virtualization, linux-kernel
On Wed, Mar 23, 2022 at 08:01:42AM -0400, Michael S. Tsirkin wrote:
> On Wed, Mar 23, 2022 at 03:57:59PM +0800, Jason Wang wrote:
> > On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
> > >
> > > The bar index is used as an index into the device's resource list
> > > and should be checked as within range for a standard bar.
> > >
> > > Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
> > >
> > > Signed-off-by: Keir Fraser <keirf@google.com>
> > > ---
> > > drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> > > drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> > > 2 files changed, 15 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > > index 5455bc041fb6..84bace98dff5 100644
> > > --- a/drivers/virtio/virtio_pci_modern.c
> > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > >
> > > for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> > > pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > > - u8 type, cap_len, id;
> > > + u8 type, cap_len, id, res_bar;
> > > u32 tmp32;
> > > u64 res_offset, res_length;
> > >
> > > @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > >
> > > /* Type, and ID match, looks good */
> > > pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > > - bar), bar);
> > > + bar), &res_bar);
> > > + if (res_bar >= PCI_STD_NUM_BARS) {
> > > + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> > > + __func__, res_bar);
> > > + continue;
> > > + }
> > >
> > > /* Read the lower 32bit of length and offset */
> > > pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
>
> In fact, the spec says such BAR values are reserved, not bad, so
> the capabiluty should be ignored, they should not cause the driver to error out
> or print errors.
Ah yes, so I see. It makes sense then to silently ignore the capability and print nothing.
I will fix it.
> > > @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > > length_hi), &tmp32);
> > > res_length |= ((u64)tmp32) << 32;
> > >
> > > + *bar = res_bar;
> > > *offset = res_offset;
> > > *len = res_length;
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > > index e8b3ff2b9fbc..a6911d1e212a 100644
> > > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > > @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> > > pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > > &length);
> > >
> > > + if (bar >= PCI_STD_NUM_BARS) {
> > > + dev_err(&dev->dev,
> > > + "virtio_pci: bad capability bar %u\n", bar);
>
> In fact, I would say the issue is less that bar is reserved.
> The real issue is that the value apparently changed since
> we read it the first time. I think it's a good idea to
> reflect that in the message. Maybe find_capability should return
> the capability structure so we don't need to re-read it from
> the device?
I will have a look and fix it up one way or the other, and respin
this patch.
Thanks,
Keir
> > > + return NULL;
> > > + }
> > > +
> > > if (length <= start) {
> > > dev_err(&dev->dev,
> > > "virtio_pci: bad capability len %u (>%u expected)\n",
> > > @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> > > &bar);
> > >
> > > /* Ignore structures with reserved BAR values */
> > > - if (bar > 0x5)
> > > + if (bar >= PCI_STD_NUM_BARS)
> > > continue;
> >
> > Just notice that the spec said:
> >
> > "
> > values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
> > the function located beginning at 10h in PCI Configuration Space and
> > used to map the structure into Memory or I/O Space. The BAR is
> > permitted to be either 32-bit or 64-bit, it can map Memory Space or
> > I/O Space.
> >
> > Any other value is reserved for future use.
> > "
> > So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
> > this and other places.
> >
> > Thanks
>
> It does not matter much IMHO, the reason spec uses 0 to 0x5 is precisely
> because that's the standard number of BARs. Both ways work as long as we
> are consistent, and I guess PCI_STD_NUM_BARS might be preferable since
> people tend to copy paste values.
>
> > >
> > > if (type == cfg_type) {
> > > --
> > > 2.35.1.894.gb6a874cedc-goog
> > >
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] virtio: pci: sanity check bar indexes
2022-03-23 13:21 ` Keir Fraser
@ 2022-03-23 13:23 ` Michael S. Tsirkin
0 siblings, 0 replies; 7+ messages in thread
From: Michael S. Tsirkin @ 2022-03-23 13:23 UTC (permalink / raw)
To: Keir Fraser; +Cc: Jason Wang, kernel-team, virtualization, linux-kernel
On Wed, Mar 23, 2022 at 01:21:55PM +0000, Keir Fraser wrote:
> On Wed, Mar 23, 2022 at 08:01:42AM -0400, Michael S. Tsirkin wrote:
> > On Wed, Mar 23, 2022 at 03:57:59PM +0800, Jason Wang wrote:
> > > On Tue, Mar 22, 2022 at 11:20 PM Keir Fraser <keirf@google.com> wrote:
> > > >
> > > > The bar index is used as an index into the device's resource list
> > > > and should be checked as within range for a standard bar.
> > > >
> > > > Also clean up an existing check to consistently use PCI_STD_NUM_BARS.
> > > >
> > > > Signed-off-by: Keir Fraser <keirf@google.com>
> > > > ---
> > > > drivers/virtio/virtio_pci_modern.c | 10 ++++++++--
> > > > drivers/virtio/virtio_pci_modern_dev.c | 8 +++++++-
> > > > 2 files changed, 15 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > > > index 5455bc041fb6..84bace98dff5 100644
> > > > --- a/drivers/virtio/virtio_pci_modern.c
> > > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > > @@ -293,7 +293,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > > >
> > > > for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
> > > > pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
> > > > - u8 type, cap_len, id;
> > > > + u8 type, cap_len, id, res_bar;
> > > > u32 tmp32;
> > > > u64 res_offset, res_length;
> > > >
> > > > @@ -317,7 +317,12 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > > >
> > > > /* Type, and ID match, looks good */
> > > > pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
> > > > - bar), bar);
> > > > + bar), &res_bar);
> > > > + if (res_bar >= PCI_STD_NUM_BARS) {
> > > > + dev_err(&dev->dev, "%s: shm cap with bad bar: %d\n",
> > > > + __func__, res_bar);
> > > > + continue;
> > > > + }
> > > >
> > > > /* Read the lower 32bit of length and offset */
> > > > pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
> >
> > In fact, the spec says such BAR values are reserved, not bad, so
> > the capabiluty should be ignored, they should not cause the driver to error out
> > or print errors.
>
> Ah yes, so I see. It makes sense then to silently ignore the capability and print nothing.
> I will fix it.
>
> > > > @@ -337,6 +342,7 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
> > > > length_hi), &tmp32);
> > > > res_length |= ((u64)tmp32) << 32;
> > > >
> > > > + *bar = res_bar;
> > > > *offset = res_offset;
> > > > *len = res_length;
> > > >
> > > > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > > > index e8b3ff2b9fbc..a6911d1e212a 100644
> > > > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > > > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > > > @@ -35,6 +35,12 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
> > > > pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > > > &length);
> > > >
> > > > + if (bar >= PCI_STD_NUM_BARS) {
> > > > + dev_err(&dev->dev,
> > > > + "virtio_pci: bad capability bar %u\n", bar);
> >
> > In fact, I would say the issue is less that bar is reserved.
> > The real issue is that the value apparently changed since
> > we read it the first time. I think it's a good idea to
> > reflect that in the message. Maybe find_capability should return
> > the capability structure so we don't need to re-read it from
> > the device?
>
> I will have a look and fix it up one way or the other, and respin
> this patch.
>
> Thanks,
> Keir
BTW avoiding extra reads is good for start up speed. This is slow path,
but still.
> > > > + return NULL;
> > > > + }
> > > > +
> > > > if (length <= start) {
> > > > dev_err(&dev->dev,
> > > > "virtio_pci: bad capability len %u (>%u expected)\n",
> > > > @@ -120,7 +126,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
> > > > &bar);
> > > >
> > > > /* Ignore structures with reserved BAR values */
> > > > - if (bar > 0x5)
> > > > + if (bar >= PCI_STD_NUM_BARS)
> > > > continue;
> > >
> > > Just notice that the spec said:
> > >
> > > "
> > > values 0x0 to 0x5 specify a Base Address register (BAR) belonging to
> > > the function located beginning at 10h in PCI Configuration Space and
> > > used to map the structure into Memory or I/O Space. The BAR is
> > > permitted to be either 32-bit or 64-bit, it can map Memory Space or
> > > I/O Space.
> > >
> > > Any other value is reserved for future use.
> > > "
> > > So we probably need to stick 0x5 instead of 0x6 (PCI_STD_NUM_BARS) for
> > > this and other places.
> > >
> > > Thanks
> >
> > It does not matter much IMHO, the reason spec uses 0 to 0x5 is precisely
> > because that's the standard number of BARs. Both ways work as long as we
> > are consistent, and I guess PCI_STD_NUM_BARS might be preferable since
> > people tend to copy paste values.
> >
> > > >
> > > > if (type == cfg_type) {
> > > > --
> > > > 2.35.1.894.gb6a874cedc-goog
> > > >
> >
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-03-23 13:23 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2022-03-22 15:19 [PATCH v2] virtio: pci: sanity check bar indexes Keir Fraser
2022-03-23 7:57 ` Jason Wang
2022-03-23 9:13 ` Keir Fraser
2022-03-23 9:21 ` Jason Wang
2022-03-23 12:01 ` Michael S. Tsirkin
2022-03-23 13:21 ` Keir Fraser
2022-03-23 13:23 ` Michael S. Tsirkin
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