On Thu, Aug 16, 2018 at 02:06:46PM -0500, Gustavo A. R. Silva wrote: > 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 > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Applied with Logan's ack to for-linus for v4.19, thanks! > --- > drivers/pci/switch/switchtec.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c > index 9940cc7..54a8b30 100644 > --- a/drivers/pci/switch/switchtec.c > +++ b/drivers/pci/switch/switchtec.c > @@ -14,6 +14,8 @@ > #include <linux/poll.h> > #include <linux/wait.h> > > +#include <linux/nospec.h> > + > MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCIe Management Driver"); > MODULE_VERSION("0.1"); > MODULE_LICENSE("GPL"); > @@ -909,6 +911,8 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev, > 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; > } > -- > 2.7.4 >
