latent_entropy: fix ARM build error on earlier gcc

This fixes build errors seen on gcc-4.9.3 or gcc-5.3.1 for an ARM:

arm-soc/init/initramfs.c: In function 'error':
arm-soc/init/initramfs.c:50:1: error: unrecognizable insn:
 }
 ^
(insn 26 25 27 5 (set (reg:SI 111 [ local_entropy.243 ])
        (rotatert:SI (reg:SI 116 [ local_entropy.243 ])
            (const_int -30 [0xffffffffffffffe2]))) -1
     (nil))

Patch from PaX Team <pageexec@freemail.hu>

Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Brad Spengler <spender@grsecurity.net>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c
index 12541126575b1e2416ad48d58f1d01f8e08a5d93..8ff203ad48093f57fccf04bb9d7c9b9e1952603b 100644 (file)
--- a/scripts/gcc-plugins/latent_entropy_plugin.c
+++ b/scripts/gcc-plugins/latent_entropy_plugin.c
@@ -328,9 +328,9 @@ static enum tree_code get_op(tree *rhs)
                        op = LROTATE_EXPR;
                        /*
                         * This code limits the value of random_const to
-                        * the size of a wide int for the rotation
+                        * the size of a long for the rotation
                         */
-                       random_const &= HOST_BITS_PER_WIDE_INT - 1;
+                       random_const %= TYPE_PRECISION(long_unsigned_type_node);
                        break;
                }