From 9774a1f54f173ad18e816496c8979f1bf8ef666a Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Wed, 6 Dec 2006 20:36:56 -0800 Subject: [PATCH] [PATCH] Compile-time check re world-writeable module params One of the mistakes a module_param() user can make is to supply default value of module parameter as the last argument. module_param() accepts permissions instead. If default value is, say, 3 (-------wx), parameter becomes world-writeable. So far, the only remedy was to apply grep(1) and read drivers submitted to -mm. BTDT. With this patch applied, compiler will finally do some job. *) bounds checking on permissions *) world-writeable bit checking on permissions *) compile breakage if checks trigger First version of this check (only "& 2" part) directly caught 4 out of 7 places during my last grep. Subject: Neverending module_param() bugs [X] drivers/acpi/sbs.c:101:module_param(capacity_mode, int, CAPACITY_UNIT); [X] drivers/acpi/sbs.c:102:module_param(update_mode, int, UPDATE_MODE); [ ] drivers/acpi/sbs.c:103:module_param(update_info_mode, int, UPDATE_INFO_MODE); [ ] drivers/acpi/sbs.c:104:module_param(update_time, int, UPDATE_TIME); [ ] drivers/acpi/sbs.c:105:module_param(update_time2, int, UPDATE_TIME2); [X] drivers/char/watchdog/sbc8360.c:203:module_param(timeout, int, 27); [X] drivers/media/video/tuner-simple.c:13:module_param(offset, int, 0666); Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/moduleparam.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 7c0c2c198f..4a189dadb1 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -63,6 +63,9 @@ struct kparam_array not there, read bits mean it's readable, write bits mean it's writable. */ #define __module_param_call(prefix, name, set, get, arg, perm) \ + /* Default value instead of permissions? */ \ + static int __param_perm_check_##name __attribute__((unused)) = \ + BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)); \ static char __param_str_##name[] = prefix #name; \ static struct kernel_param const __param_##name \ __attribute_used__ \ -- 2.39.5