From 278dcfd28a0e0af539a5ef10dab713f482dd2061 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Fri, 3 Jun 2016 00:48:39 +0100 Subject: [PATCH] mtd: Disable slram and phram when locked down The slram and phram drivers both allow mapping regions of physical address space such that they can then be read and written by userland through the MTD interface. This is probably usable to manipulate hardware into overwriting kernel code on many systems. Prevent that if locked down. Signed-off-by: Ben Hutchings Gbp-Pq: Topic features/all/lockdown Gbp-Pq: Name mtd-disable-slram-and-phram-when-locked-down.patch --- drivers/mtd/devices/phram.c | 3 +++ drivers/mtd/devices/slram.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c index c467286ca00..edd50721325 100644 --- a/drivers/mtd/devices/phram.c +++ b/drivers/mtd/devices/phram.c @@ -222,6 +222,9 @@ static int phram_setup(const char *val) uint64_t len; int i, ret; + if (kernel_is_locked_down("Command line-specified device addresses")) + return -EPERM; + if (strnlen(val, sizeof(buf)) >= sizeof(buf)) parse_err("parameter too long\n"); diff --git a/drivers/mtd/devices/slram.c b/drivers/mtd/devices/slram.c index 28131a127d0..de4fe135b0e 100644 --- a/drivers/mtd/devices/slram.c +++ b/drivers/mtd/devices/slram.c @@ -227,6 +227,9 @@ static int parse_cmdline(char *devname, char *szstart, char *szlength) unsigned long devstart; unsigned long devlength; + if (kernel_is_locked_down("Command line-specified device addresses")) + return -EPERM; + if ((!devname) || (!szstart) || (!szlength)) { unregister_devices(); return(-EINVAL); -- 2.30.2