From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936612AbdGTQCN (ORCPT ); Thu, 20 Jul 2017 12:02:13 -0400 Received: from mout.kundenserver.de ([212.227.17.13]:53116 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934497AbdGTQCK (ORCPT ); Thu, 20 Jul 2017 12:02:10 -0400 From: Arnd Bergmann To: Darren Hart , Andy Shevchenko Cc: Arnd Bergmann , platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] platform/x86: alienware-wmi: fix format string overflow warning Date: Thu, 20 Jul 2017 18:00:51 +0200 Message-Id: <20170720160114.3261176-2-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20170720160114.3261176-1-arnd@arndb.de> References: <20170720160114.3261176-1-arnd@arndb.de> X-Provags-ID: V03:K0:5oubkWhIBVIIoSuoKS6I3K1gpJmGoZAt5h9lk70flgc/vSlp5iH R5RuHCLA4NlBw/x5FwmqTragBbf3LXz+g24f9+XT7X9573EV6lO9pJy7j/MlreodaMLW7M+ iHnfMDzzCfa00wDg55AhJitfyZ29D6os1tOokHY/eiEJtwvSX3PBeUCXAnBUO352Oskqsed mv9wG0OXirs92L22oFQIw== X-UI-Out-Filterresults: notjunk:1;V01:K0:/VuXnIfv0xU=:nTbg/E+DxfZoe4FQNfs8bN NGGrxX6GW3lrnV/NOjIU98BvTmHKOgAep/FKEB1lJe0eFGByxb+e079OFC9mvSyx1jRs0/FDW XGHsBpcgoOM73leTWHeMu4BxkqA/i2TkMbgmkFcEtBKd83B+4XzMDsnrClfkMkm6RRw2r02jR w4+YrruWSfG29GK14xFwwrYgqJ5dTuKaaDXmjTt6US5mqe+cvElabvipY/J/PASNyqFH0jqIB DZdph/XI41Dh0TbTRHBLhwo/uZjQkw1HJRMViIJJI2sxjzJoYSWqoSPZtL+Zb8YwOPt3GccMu rAfNpESKWetM/5Z5J/cGGjYOA8RsBSJsnbtcseKedkQjGYObD4Utrp5hV9k3QQizkSuRkWhBE 3hJCTY7YDoceplUdhQttrNr48AkCYu0F6OIMreT5kXG8MAjdpGEuz1+GLkA6aC0IOOYKx/WgY cUoq4Q3A5PdpvIvQ8eqsNT4bAIO7lopljFYKHsNj1J7vhZ2mY+Uc5qHoTrDyVwP0HDiUY+hrZ bfauoybcd6j72yfaD0kE3NCcubaCKXMVGhEu2Nkje40dI62M2NDwoUNGAsbUFgeescbRvwjWx n3hnUlGsuT1dYW6Hcm8ByzKe79206krmTE57UP53jVbYo8BDjVcfVgf3Sndt0VYJABx9CVUxC I3/gqWyM+aLbQWcJX0GT/G16OaVdnhkwF1L0McOZeiGiCZYhprLzj0H7sy9KnyJGSdNJxvmMI QmJeBvuqX41XixQC7ymePitoA9AwrfmuxPIVNw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org gcc points out a possible format string overflow for a large value of 'zone': drivers/platform/x86/alienware-wmi.c: In function 'alienware_wmi_init': drivers/platform/x86/alienware-wmi.c:461:24: error: '%02X' directive writing between 2 and 8 bytes into a region of size 6 [-Werror=format-overflow=] sprintf(buffer, "zone%02X", i); ^~~~ drivers/platform/x86/alienware-wmi.c:461:19: note: directive argument in the range [0, 2147483646] sprintf(buffer, "zone%02X", i); ^~~~~~~~~~ drivers/platform/x86/alienware-wmi.c:461:3: note: 'sprintf' output between 7 and 13 bytes into a destination of size 10 This replaces the 'int' variable with an 'u8' to make sure it always fits, renaming the variable to 'zone' for clarity. Unfortunately, gcc-7.1.1 still warns about it with that change, which seems to be unintended by the gcc developers. I have opened a bug against gcc with a reduced test case. As a workaround, I also change the format string to use "%02hhX", which shuts up the warning in that version. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81483 Link: https://patchwork.ozlabs.org/patch/788415/ Suggested-by: Andy Shevchenko Signed-off-by: Arnd Bergmann --- v2: completely rewrite the patch after discussing with Andy --- drivers/platform/x86/alienware-wmi.c | 38 ++++++++++++++++++------------------ 1 file changed, 19 insertions(+), 19 deletions(-) diff --git a/drivers/platform/x86/alienware-wmi.c b/drivers/platform/x86/alienware-wmi.c index 0831b428c217..c56a9ecba959 100644 --- a/drivers/platform/x86/alienware-wmi.c +++ b/drivers/platform/x86/alienware-wmi.c @@ -255,12 +255,12 @@ static int parse_rgb(const char *buf, struct platform_zone *zone) static struct platform_zone *match_zone(struct device_attribute *attr) { - int i; - for (i = 0; i < quirks->num_zones; i++) { - if ((struct device_attribute *)zone_data[i].attr == attr) { + u8 zone; + for (zone = 0; zone < quirks->num_zones; zone++) { + if ((struct device_attribute *)zone_data[zone].attr == attr) { pr_debug("alienware-wmi: matched zone location: %d\n", - zone_data[i].location); - return &zone_data[i]; + zone_data[zone].location); + return &zone_data[zone]; } } return NULL; @@ -420,7 +420,7 @@ static DEVICE_ATTR(lighting_control_state, 0644, show_control_state, static int alienware_zone_init(struct platform_device *dev) { - int i; + u8 zone; char buffer[10]; char *name; @@ -457,19 +457,19 @@ static int alienware_zone_init(struct platform_device *dev) if (!zone_data) return -ENOMEM; - for (i = 0; i < quirks->num_zones; i++) { - sprintf(buffer, "zone%02X", i); + for (zone = 0; zone < quirks->num_zones; zone++) { + sprintf(buffer, "zone%02hhX", zone); name = kstrdup(buffer, GFP_KERNEL); if (name == NULL) return 1; - sysfs_attr_init(&zone_dev_attrs[i].attr); - zone_dev_attrs[i].attr.name = name; - zone_dev_attrs[i].attr.mode = 0644; - zone_dev_attrs[i].show = zone_show; - zone_dev_attrs[i].store = zone_set; - zone_data[i].location = i; - zone_attrs[i] = &zone_dev_attrs[i].attr; - zone_data[i].attr = &zone_dev_attrs[i]; + sysfs_attr_init(&zone_dev_attrs[zone].attr); + zone_dev_attrs[zone].attr.name = name; + zone_dev_attrs[zone].attr.mode = 0644; + zone_dev_attrs[zone].show = zone_show; + zone_dev_attrs[zone].store = zone_set; + zone_data[zone].location = zone; + zone_attrs[zone] = &zone_dev_attrs[zone].attr; + zone_data[zone].attr = &zone_dev_attrs[zone]; } zone_attrs[quirks->num_zones] = &dev_attr_lighting_control_state.attr; zone_attribute_group.attrs = zone_attrs; @@ -484,9 +484,9 @@ static void alienware_zone_exit(struct platform_device *dev) sysfs_remove_group(&dev->dev.kobj, &zone_attribute_group); led_classdev_unregister(&global_led); if (zone_dev_attrs) { - int i; - for (i = 0; i < quirks->num_zones; i++) - kfree(zone_dev_attrs[i].attr.name); + u8 zone; + for (zone = 0; zone < quirks->num_zones; zone++) + kfree(zone_dev_attrs[zone].attr.name); } kfree(zone_dev_attrs); kfree(zone_data); -- 2.9.0