Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752338AbdLALdV (ORCPT ); Fri, 1 Dec 2017 06:33:21 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:2193 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752025AbdLALdT (ORCPT ); Fri, 1 Dec 2017 06:33:19 -0500 To: , , "linux-kernel@vger.kernel.org" , LinuxArm From: Ding Tianhong Subject: [PATCH] ubsan: don't handle misaligned address when support unaligned access Message-ID: <9cdc75c4-326f-5adb-b32c-c95e1f3211ce@huawei.com> Date: Fri, 1 Dec 2017 19:32:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.23.32] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1701 Lines: 46 The ubsan always report Warning just like: UBSAN: Undefined behaviour in ../include/linux/etherdevice.h:386:9 load of misaligned address ffffffc069ba0482 for type 'long unsigned int' which requires 8 byte alignment CPU: 0 PID: 901 Comm: sshd Not tainted 4.xx+ #1 Hardware name: linux,dummy-virt (DT) Call trace: [] dump_backtrace+0x0/0x348 [] show_stack+0x20/0x30 [] dump_stack+0x144/0x1b4 [] ubsan_epilogue+0x18/0x74 [] __ubsan_handle_type_mismatch+0x1a0/0x25c [] dev_gro_receive+0x17d8/0x1830 [] napi_gro_receive+0x30/0x158 [] virtnet_receive+0xad4/0x1fa8 The reason is that when enable the CONFIG_UBSAN_ALIGNMENT, the ubsan will report the unaligned access even if the system support it (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y), it will produce a lot of noise in the log and cause confusion. This patch will close the detection of unaligned access when the system support unaligned access. Signed-off-by: Ding Tianhong --- lib/ubsan.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/ubsan.c b/lib/ubsan.c index fb0409d..278b4c3 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -321,7 +321,8 @@ void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, if (!ptr) handle_null_ptr_deref(data); - else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) + else if (data->alignment && !IS_ALIGNED(ptr, data->alignment) && + !IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) handle_missaligned_access(data, ptr); else handle_object_size_mismatch(data, ptr); -- 1.8.3.1