Dan Williams <dan.j.williams@xxxxxxxxx> writes: > Dan reports that smatch thinks userspace can craft an out-of-bound bus > family number. However, nd_cmd_clear_to_send() blocks all non-zero > values of bus-family since only the kernel can initiate these commands. > However, in the speculation path, family is a user controlled array > index value so mask it for speculation safety. Also, since the > nd_cmd_clear_to_send() safety is non-obvious and possibly may change in > the future include input validation is if userspace could get past the > nd_cmd_clear_to_send() gatekeeper. > > Link: http://lore.kernel.org/r/20201111113000.GA1237157@mwanda > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > Fixes: 6450ddbd5d8e ("ACPI: NFIT: Define runtime firmware activation commands") > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > drivers/acpi/nfit/core.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c > index cda7b6c52504..b11b08a60684 100644 > --- a/drivers/acpi/nfit/core.c > +++ b/drivers/acpi/nfit/core.c > @@ -5,6 +5,7 @@ > #include <linux/list_sort.h> > #include <linux/libnvdimm.h> > #include <linux/module.h> > +#include <linux/nospec.h> > #include <linux/mutex.h> > #include <linux/ndctl.h> > #include <linux/sysfs.h> > @@ -479,8 +480,11 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm, > cmd_mask = nd_desc->cmd_mask; > if (cmd == ND_CMD_CALL && call_pkg->nd_family) { > family = call_pkg->nd_family; > - if (!test_bit(family, &nd_desc->bus_family_mask)) > + if (family > NVDIMM_BUS_FAMILY_MAX || > + !test_bit(family, &nd_desc->bus_family_mask)) > return -EINVAL; > + family = array_index_nospec(family, > + NVDIMM_BUS_FAMILY_MAX + 1); > dsm_mask = acpi_desc->family_dsm_mask[family]; > guid = to_nfit_bus_uuid(family); > } else { Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
