| Message ID | 20210220062837.1683159-1-kw@linux.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI/switchtec: Fix Spectre v1 vulnerability | expand |
On 2021-02-19 11:28 p.m., Krzysztof Wilczyński wrote: > The "partition" member of the struct switchtec_ioctl_pff_port can be > indirectly controlled from user-space through an IOCTL that the device > driver provides enabling conversion between a PCI Function Framework > (PFF) number and Switchtec logical port ID and partition number, thus > allowing for command-line tooling [1] interact with the device from > user-space. > > This can lead to potential exploitation of the Spectre variant 1 [2] > vulnerability since the value of the partition is then used directly > as an index to mmio_part_cfg_all of the struct switchtec_dev to retrieve > configuration from Switchtec for a specific partition number. > > Fix this by sanitizing the value coming from user-space through the > available IOCTL before it's then used as an index to mmio_part_cfg_all. > > This issue was detected with the help of Smatch: > > drivers/pci/switch/switchtec.c:1118 ioctl_port_to_pff() warn: > potential spectre issue 'stdev->mmio_part_cfg_all' [r] (local cap) > > Notice that given that speculation windows are large, the policy is > to kill the speculation on the first load and not worry if it can be > completed with a dependent load/store [3]. > > Related commit 46feb6b495f7 ("switchtec: Fix Spectre v1 vulnerability"). > > 1. https://github.com/Microsemi/switchtec-user/blob/master/lib/platform/linux.c > 2. https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/spectre.html > 3. https://lore.kernel.org/lkml/CAPcyv4gLKYiCtXsKFX2FY+rW93aRtQt9zB8hU1hMsj770m8gxQ@mail.gmail.com/ > > Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Looks good to me. Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Thanks! Logan
On Sat, Feb 20, 2021 at 06:28:37AM +0000, Krzysztof Wilczyński wrote: > The "partition" member of the struct switchtec_ioctl_pff_port can be > indirectly controlled from user-space through an IOCTL that the device > driver provides enabling conversion between a PCI Function Framework > (PFF) number and Switchtec logical port ID and partition number, thus > allowing for command-line tooling [1] interact with the device from > user-space. > > This can lead to potential exploitation of the Spectre variant 1 [2] > vulnerability since the value of the partition is then used directly > as an index to mmio_part_cfg_all of the struct switchtec_dev to retrieve > configuration from Switchtec for a specific partition number. > > Fix this by sanitizing the value coming from user-space through the > available IOCTL before it's then used as an index to mmio_part_cfg_all. > > This issue was detected with the help of Smatch: > > drivers/pci/switch/switchtec.c:1118 ioctl_port_to_pff() warn: > potential spectre issue 'stdev->mmio_part_cfg_all' [r] (local cap) > > Notice that given that speculation windows are large, the policy is > to kill the speculation on the first load and not worry if it can be > completed with a dependent load/store [3]. > > Related commit 46feb6b495f7 ("switchtec: Fix Spectre v1 vulnerability"). > > 1. https://github.com/Microsemi/switchtec-user/blob/master/lib/platform/linux.c > 2. https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/spectre.html > 3. https://lore.kernel.org/lkml/CAPcyv4gLKYiCtXsKFX2FY+rW93aRtQt9zB8hU1hMsj770m8gxQ@mail.gmail.com/ > > Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Applied with Logan's ack to for-linus for v5.12, thanks! > --- > drivers/pci/switch/switchtec.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c > index ba52459928f7..bb6957101fc0 100644 > --- a/drivers/pci/switch/switchtec.c > +++ b/drivers/pci/switch/switchtec.c > @@ -1112,12 +1112,15 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev, > if (copy_from_user(&p, up, sizeof(p))) > return -EFAULT; > > - if (p.partition == SWITCHTEC_IOCTL_EVENT_LOCAL_PART_IDX) > + if (p.partition == SWITCHTEC_IOCTL_EVENT_LOCAL_PART_IDX) { > pcfg = stdev->mmio_part_cfg; > - else if (p.partition < stdev->partition_count) > + } else if (p.partition < stdev->partition_count) { > + p.partition = array_index_nospec(p.partition, > + stdev->partition_count); > pcfg = &stdev->mmio_part_cfg_all[p.partition]; > - else > + } else { > return -EINVAL; > + } > > switch (p.port) { > case 0: > -- > 2.30.0 >
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c index ba52459928f7..bb6957101fc0 100644 --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -1112,12 +1112,15 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev, if (copy_from_user(&p, up, sizeof(p))) return -EFAULT; - if (p.partition == SWITCHTEC_IOCTL_EVENT_LOCAL_PART_IDX) + if (p.partition == SWITCHTEC_IOCTL_EVENT_LOCAL_PART_IDX) { pcfg = stdev->mmio_part_cfg; - else if (p.partition < stdev->partition_count) + } else if (p.partition < stdev->partition_count) { + p.partition = array_index_nospec(p.partition, + stdev->partition_count); pcfg = &stdev->mmio_part_cfg_all[p.partition]; - else + } else { return -EINVAL; + } switch (p.port) { case 0:
The "partition" member of the struct switchtec_ioctl_pff_port can be indirectly controlled from user-space through an IOCTL that the device driver provides enabling conversion between a PCI Function Framework (PFF) number and Switchtec logical port ID and partition number, thus allowing for command-line tooling [1] interact with the device from user-space. This can lead to potential exploitation of the Spectre variant 1 [2] vulnerability since the value of the partition is then used directly as an index to mmio_part_cfg_all of the struct switchtec_dev to retrieve configuration from Switchtec for a specific partition number. Fix this by sanitizing the value coming from user-space through the available IOCTL before it's then used as an index to mmio_part_cfg_all. This issue was detected with the help of Smatch: drivers/pci/switch/switchtec.c:1118 ioctl_port_to_pff() warn: potential spectre issue 'stdev->mmio_part_cfg_all' [r] (local cap) Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [3]. Related commit 46feb6b495f7 ("switchtec: Fix Spectre v1 vulnerability"). 1. https://github.com/Microsemi/switchtec-user/blob/master/lib/platform/linux.c 2. https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/spectre.html 3. https://lore.kernel.org/lkml/CAPcyv4gLKYiCtXsKFX2FY+rW93aRtQt9zB8hU1hMsj770m8gxQ@mail.gmail.com/ Signed-off-by: Krzysztof Wilczyński <kw@linux.com> --- drivers/pci/switch/switchtec.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)