* Re: [PATCH v3] virtio: pci: check bar values read from virtio config space [not found] <20220323140727.3499235-1-keirf@google.com> @ 2022-03-30 2:43 ` Jason Wang 2022-03-30 6:35 ` Michael S. Tsirkin 0 siblings, 1 reply; 2+ messages in thread From: Jason Wang @ 2022-03-30 2:43 UTC (permalink / raw) To: Keir Fraser; +Cc: virtualization, kernel-team, linux-kernel, Michael S. Tsirkin On Wed, Mar 23, 2022 at 10:07 PM Keir Fraser <keirf@google.com> wrote: > > virtio pci config structures may in future have non-standard bar > values in the bar field. We should anticipate this by skipping any > structures containing such a reserved value. > > The bar value should never change: check for harmful modified values > we re-read it from the config space in vp_modern_map_capability(). > > Also clean up an existing check to consistently use PCI_STD_NUM_BARS. > > Signed-off-by: Keir Fraser <keirf@google.com> Acked-by: Jason Wang <jasowang@redhat.com> > --- > drivers/virtio/virtio_pci_modern.c | 12 +++++++++--- > drivers/virtio/virtio_pci_modern_dev.c | 9 ++++++++- > 2 files changed, 17 insertions(+), 4 deletions(-) > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index 5455bc041fb6..6adfcd0297a7 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; > > @@ -315,9 +315,14 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id, > if (id != required_id) > continue; > > - /* 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) > + continue; > + > + /* Type and ID match, and the BAR value isn't reserved. > + * Looks good. > + */ > > /* 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..591738ad3d56 100644 > --- a/drivers/virtio/virtio_pci_modern_dev.c > +++ b/drivers/virtio/virtio_pci_modern_dev.c > @@ -35,6 +35,13 @@ 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); > > + /* Check if the BAR may have changed since we requested the region. */ > + if (bar >= PCI_STD_NUM_BARS || !(mdev->modern_bars & (1 << bar))) { > + dev_err(&dev->dev, > + "virtio_pci: bar unexpectedly changed to %u\n", bar); > + return NULL; > + } > + > if (length <= start) { > dev_err(&dev->dev, > "virtio_pci: bad capability len %u (>%u expected)\n", > @@ -120,7 +127,7 @@ 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 > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v3] virtio: pci: check bar values read from virtio config space 2022-03-30 2:43 ` [PATCH v3] virtio: pci: check bar values read from virtio config space Jason Wang @ 2022-03-30 6:35 ` Michael S. Tsirkin 0 siblings, 0 replies; 2+ messages in thread From: Michael S. Tsirkin @ 2022-03-30 6:35 UTC (permalink / raw) To: Jason Wang; +Cc: Keir Fraser, kernel-team, linux-kernel, virtualization On Wed, Mar 30, 2022 at 10:43:40AM +0800, Jason Wang wrote: > On Wed, Mar 23, 2022 at 10:07 PM Keir Fraser <keirf@google.com> wrote: > > > > virtio pci config structures may in future have non-standard bar > > values in the bar field. We should anticipate this by skipping any > > structures containing such a reserved value. > > > > The bar value should never change: check for harmful modified values > > we re-read it from the config space in vp_modern_map_capability(). > > > > Also clean up an existing check to consistently use PCI_STD_NUM_BARS. > > > > Signed-off-by: Keir Fraser <keirf@google.com> > > Acked-by: Jason Wang <jasowang@redhat.com> > Thanks! I don't want to rebase anymore though so not adding this ack. Sorry! > > drivers/virtio/virtio_pci_modern.c | 12 +++++++++--- > > drivers/virtio/virtio_pci_modern_dev.c | 9 ++++++++- > > 2 files changed, 17 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > > index 5455bc041fb6..6adfcd0297a7 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; > > > > @@ -315,9 +315,14 @@ static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id, > > if (id != required_id) > > continue; > > > > - /* 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) > > + continue; > > + > > + /* Type and ID match, and the BAR value isn't reserved. > > + * Looks good. > > + */ > > > > /* 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..591738ad3d56 100644 > > --- a/drivers/virtio/virtio_pci_modern_dev.c > > +++ b/drivers/virtio/virtio_pci_modern_dev.c > > @@ -35,6 +35,13 @@ 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); > > > > + /* Check if the BAR may have changed since we requested the region. */ > > + if (bar >= PCI_STD_NUM_BARS || !(mdev->modern_bars & (1 << bar))) { > > + dev_err(&dev->dev, > > + "virtio_pci: bar unexpectedly changed to %u\n", bar); > > + return NULL; > > + } > > + > > if (length <= start) { > > dev_err(&dev->dev, > > "virtio_pci: bad capability len %u (>%u expected)\n", > > @@ -120,7 +127,7 @@ 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 > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-03-30 2:43 ` [PATCH v3] virtio: pci: check bar values read from virtio config space Jason Wang
2022-03-30 6:35 ` Michael S. Tsirkin
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