media: dvb_ca_en50221: prevent using slot_info for Spectre attacs

slot can be controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability,
as warned by smatch:
	drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn: potential spectre issue 'ca->slot_info' (local cap)

Acked-by: "Jasmin J." <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab 2018-05-15 08:31:38 -04:00
parent 782b9d2011
commit 4f5ab5d7a5

View File

@ -31,6 +31,7 @@
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/nospec.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
@ -1476,6 +1477,7 @@ static ssize_t dvb_ca_en50221_io_write(struct file *file,
if (slot >= ca->slot_count)
return -EINVAL;
slot = array_index_nospec(slot, ca->slot_count);
sl = &ca->slot_info[slot];
/* check if the slot is actually running */