4.9-stable review patch. If anyone has any objections, please let me know.
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From: Gustavo A. R. Silva gustavo@embeddedor.com
commit de916736aaaadddbd6061472969f667b14204aa9 upstream.
val 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/misc/hmc6352.c:54 compass_store() warn: potential spectre issue 'map' [r]
Fix this by sanitizing val before using it to index map
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/misc/hmc6352.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/misc/hmc6352.c +++ b/drivers/misc/hmc6352.c @@ -27,6 +27,7 @@ #include <linux/err.h> #include <linux/delay.h> #include <linux/sysfs.h> +#include <linux/nospec.h>
static DEFINE_MUTEX(compass_mutex);
@@ -50,6 +51,7 @@ static int compass_store(struct device * return ret; if (val >= strlen(map)) return -EINVAL; + val = array_index_nospec(val, strlen(map)); mutex_lock(&compass_mutex); ret = compass_command(c, map[val]); mutex_unlock(&compass_mutex);