| From 46feb6b495f7628a6dbf36c4e6d80faf378372d4 Mon Sep 17 00:00:00 2001 |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| Date: Thu, 16 Aug 2018 14:06:46 -0500 |
| Subject: switchtec: Fix Spectre v1 vulnerability |
| |
| From: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| |
| commit 46feb6b495f7628a6dbf36c4e6d80faf378372d4 upstream. |
| |
| p.port can is indirectly controlled by user-space, hence leading to |
| a potential exploitation of the Spectre variant 1 vulnerability. |
| |
| This issue was detected with the help of Smatch: |
| |
| drivers/pci/switch/switchtec.c:912 ioctl_port_to_pff() warn: potential spectre issue 'pcfg->dsp_pff_inst_id' [r] |
| |
| Fix this by sanitizing p.port before using it to index |
| pcfg->dsp_pff_inst_id |
| |
| 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 [1]. |
| |
| [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 |
| |
| Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> |
| Acked-by: Logan Gunthorpe <logang@deltatee.com> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/pci/switch/switchtec.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| --- a/drivers/pci/switch/switchtec.c |
| +++ b/drivers/pci/switch/switchtec.c |
| @@ -24,6 +24,8 @@ |
| #include <linux/cdev.h> |
| #include <linux/wait.h> |
| |
| +#include <linux/nospec.h> |
| + |
| MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCIe Management Driver"); |
| MODULE_VERSION("0.1"); |
| MODULE_LICENSE("GPL"); |
| @@ -1173,6 +1175,8 @@ static int ioctl_port_to_pff(struct swit |
| default: |
| if (p.port > ARRAY_SIZE(pcfg->dsp_pff_inst_id)) |
| return -EINVAL; |
| + p.port = array_index_nospec(p.port, |
| + ARRAY_SIZE(pcfg->dsp_pff_inst_id) + 1); |
| p.pff = ioread32(&pcfg->dsp_pff_inst_id[p.port - 1]); |
| break; |
| } |