net: socket: fix potential spectre v1 gadget in socketcall

'call' is a user-controlled value, so sanitize the array index after the
bounds check to avoid speculating past the bounds of the 'nargs' array.

Found with the help of Smatch:

net/socket.c:2508 __do_sys_socketcall() warn: potential spectre issue
'nargs' [r] (local cap)

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jeremy Cline 2018-07-27 22:43:01 +00:00 committed by David S. Miller
parent 958b4cd8fa
commit c8e8cd579b

View File

@ -89,6 +89,7 @@
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@ -2522,6 +2523,7 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
if (call < 1 || call > SYS_SENDMMSG)
return -EINVAL;
call = array_index_nospec(call, SYS_SENDMMSG + 1);
len = nargs[call];
if (len > sizeof(a))