From: Jordy Zomer jordy@jordyzomer.github.io
[ Upstream commit cd9c88da171a62c4b0f1c70e50c75845969fbc18 ]
It appears like cmd could be a Spectre v1 gadget as it's supplied by a user and used as an array index. Prevent the contents of kernel memory from being leaked to userspace via speculative execution by using array_index_nospec.
Signed-off-by: Jordy Zomer jordy@pwning.systems Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-ioctl.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index eb2659a12310..70245782e7f6 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -16,6 +16,7 @@ #include <linux/dm-ioctl.h> #include <linux/hdreg.h> #include <linux/compat.h> +#include <linux/nospec.h>
#include <asm/uaccess.h>
@@ -1642,6 +1643,7 @@ static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags) if (unlikely(cmd >= ARRAY_SIZE(_ioctls))) return NULL;
+ cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls)); *ioctl_flags = _ioctls[cmd].flags; return _ioctls[cmd].fn; }