| Message ID | 20181016101645.GA24870@embeddedor.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | usb: gadget: storage: Fix Spectre v1 vulnerability | expand |
Hi Greg, "Gustavo A. R. Silva" <gustavo@embeddedor.com> writes: > num can be 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/usb/gadget/function/f_mass_storage.c:3177 fsg_lun_make() warn: > potential spectre issue 'fsg_opts->common->luns' [r] (local cap) > > Fix this by sanitizing num before using it to index > fsg_opts->common->luns > > 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@vger.kernel.org > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Can you still take this as an urgent fix? Acked-by: Felipe Balbi <felipe.balbi@intel.com>
On Tue, Oct 16, 2018 at 02:28:19PM +0300, Felipe Balbi wrote: > > Hi Greg, > > "Gustavo A. R. Silva" <gustavo@embeddedor.com> writes: > > > num can be 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/usb/gadget/function/f_mass_storage.c:3177 fsg_lun_make() warn: > > potential spectre issue 'fsg_opts->common->luns' [r] (local cap) > > > > Fix this by sanitizing num before using it to index > > fsg_opts->common->luns > > > > 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@vger.kernel.org > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > > Can you still take this as an urgent fix? > > Acked-by: Felipe Balbi <felipe.balbi@intel.com> Yes, will do so, thanks. greg k-h > > -- > balbi
diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c index cb402e7a..043f97a 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -221,6 +221,8 @@ #include <linux/usb/gadget.h> #include <linux/usb/composite.h> +#include <linux/nospec.h> + #include "configfs.h" @@ -3152,6 +3154,7 @@ static struct config_group *fsg_lun_make(struct config_group *group, fsg_opts = to_fsg_opts(&group->cg_item); if (num >= FSG_MAX_LUNS) return ERR_PTR(-ERANGE); + num = array_index_nospec(num, FSG_MAX_LUNS); mutex_lock(&fsg_opts->lock); if (fsg_opts->refcnt || fsg_opts->common->luns[num]) {
num can be 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/usb/gadget/function/f_mass_storage.c:3177 fsg_lun_make() warn: potential spectre issue 'fsg_opts->common->luns' [r] (local cap) Fix this by sanitizing num before using it to index fsg_opts->common->luns 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@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/usb/gadget/function/f_mass_storage.c | 3 +++ 1 file changed, 3 insertions(+)