[PATCH] latent_entropy: fix ARM build error on earlier gcc

[PATCH] latent_entropy: fix ARM build error on earlier gcc

[Kees Cook]

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>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 scripts/gcc-plugins/latent_entropy_plugin.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c
index ff1939b804ae..eb1964084ccd 100644
--- 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;
 		}
 
-- 
2.7.4


-- 
Kees Cook
Nexus Security

Re: [PATCH] latent_entropy: fix ARM build error on earlier gcc

[PaX Team]

On 16 Dec 2016 at 13:06, Kees Cook wrote:

> 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>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Cc: stable@vger.kernel.org perhaps?

Re: [PATCH] latent_entropy: fix ARM build error on earlier gcc

[Kees Cook]

On Fri, Dec 16, 2016 at 2:17 PM, PaX Team <pageexec@freemail.hu> wrote:
> On 16 Dec 2016 at 13:06, Kees Cook wrote:
>
>> 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>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>
> Cc: stable@vger.kernel.org perhaps?

Ah yes, good catch.

-Kees

-- 
Kees Cook
Nexus Security