From 4fd3e4ef1f7e94299b42c2f473e196d0b8c114d0 Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Fri, 30 Jun 2017 22:07:03 +0800 Subject: [PATCH 1/3] modpost: abort if module name is too long Module name has a limited length, but currently the build system allows the build finishing even if the module name is too long. CC /root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.o /root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.c:9:2: warning: initializer-string for array of chars is too long [enabled by default] .name = KBUILD_MODNAME, ^ but it's merely a warning. This patch adds the check of the module name length in modpost and stops the build properly. Signed-off-by: Wanlong Gao Signed-off-by: Jessica Yu --- scripts/mod/modpost.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 48397feb08fb..301c27740c5c 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -47,6 +47,12 @@ enum export { export_unused_gpl, export_gpl_future, export_unknown }; +/* In kernel, this size is defined in linux/module.h; + * here we use Elf_Addr instead of long for covering cross-compile + */ + +#define MODULE_NAME_LEN (64 - sizeof(Elf_Addr)) + #define PRINTF __attribute__ ((format (printf, 1, 2))) PRINTF void fatal(const char *fmt, ...) @@ -2116,6 +2122,23 @@ static void check_exports(struct module *mod) } } +static int check_modname_len(struct module *mod) +{ + const char *mod_name; + + mod_name = strrchr(mod->name, '/'); + if (mod_name == NULL) + mod_name = mod->name; + else + mod_name++; + if (strlen(mod_name) >= MODULE_NAME_LEN) { + merror("module name is too long [%s.ko]\n", mod->name); + return 1; + } + + return 0; +} + /** * Header for the generated file **/ @@ -2155,11 +2178,6 @@ static void add_staging_flag(struct buffer *b, const char *name) buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n"); } -/* In kernel, this size is defined in linux/module.h; - * here we use Elf_Addr instead of long for covering cross-compile - */ -#define MODULE_NAME_LEN (64 - sizeof(Elf_Addr)) - /** * Record CRCs for unresolved symbols **/ @@ -2490,6 +2508,7 @@ int main(int argc, char **argv) buf.pos = 0; + err |= check_modname_len(mod); add_header(&buf, mod); add_intree_flag(&buf, !external_module); add_staging_flag(&buf, mod->name); From 5279631271b32201243c60308a8987bd585e4460 Mon Sep 17 00:00:00 2001 From: Zhou Chengming Date: Fri, 7 Jul 2017 11:15:58 +0800 Subject: [PATCH 2/3] module: fix ddebug_remove_module() ddebug_remove_module() use mod->name to find the ddebug_table of the module and remove it. But dynamic_debug_setup() use the first _ddebug->modname to create ddebug_table for the module. It's ok when the _ddebug->modname is the same with the mod->name. But livepatch module is special, it may contain _ddebugs of other modules, the modname of which is different from the name of livepatch module. So ddebug_remove_module() can't use mod->name to find the right ddebug_table and remove it. It can cause kernel crash when we cat the file /dynamic_debug/control. Signed-off-by: Zhou Chengming Signed-off-by: Jessica Yu --- kernel/module.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 40f983cbea81..de66ec825992 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2707,21 +2707,21 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) } #endif /* CONFIG_KALLSYMS */ -static void dynamic_debug_setup(struct _ddebug *debug, unsigned int num) +static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug, unsigned int num) { if (!debug) return; #ifdef CONFIG_DYNAMIC_DEBUG - if (ddebug_add_module(debug, num, debug->modname)) + if (ddebug_add_module(debug, num, mod->name)) pr_err("dynamic debug error adding module: %s\n", debug->modname); #endif } -static void dynamic_debug_remove(struct _ddebug *debug) +static void dynamic_debug_remove(struct module *mod, struct _ddebug *debug) { if (debug) - ddebug_remove_module(debug->modname); + ddebug_remove_module(mod->name); } void * __weak module_alloc(unsigned long size) @@ -3715,7 +3715,7 @@ static int load_module(struct load_info *info, const char __user *uargs, goto free_arch_cleanup; } - dynamic_debug_setup(info->debug, info->num_debug); + dynamic_debug_setup(mod, info->debug, info->num_debug); /* Ftrace init must be called in the MODULE_STATE_UNFORMED state */ ftrace_module_init(mod); @@ -3779,7 +3779,7 @@ static int load_module(struct load_info *info, const char __user *uargs, module_disable_nx(mod); ddebug_cleanup: - dynamic_debug_remove(info->debug); + dynamic_debug_remove(mod, info->debug); synchronize_sched(); kfree(mod->args); free_arch_cleanup: From 0bf8bf50eddc7511b52461bae798cbfaa0157a34 Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Mon, 24 Jul 2017 18:27:25 -0700 Subject: [PATCH 3/3] module: Remove const attribute from alias for MODULE_DEVICE_TABLE MODULE_DEVICE_TABLE(type, name) creates an alias of type 'extern const typeof(name)'. If 'name' is already constant the 'const' attribute is specified twice, which is not allowed in C89 (see discussion at https://lkml.org/lkml/2017/5/23/1440). Since the kernel is built with -std=gnu89 clang generates warnings like this: drivers/thermal/x86_pkg_temp_thermal.c:509:1: warning: duplicate 'const' declaration specifier [-Wduplicate-decl-specifier] MODULE_DEVICE_TABLE(x86cpu, pkg_temp_thermal_ids); ^ ./include/linux/module.h:212:8: note: expanded from macro 'MODULE_DEVICE_TABLE' extern const typeof(name) __mod_##type##__##name##_device_table Remove the const attribute from the alias to avoid the duplicate specifier. After all it is only an alias and the attribute shouldn't have any effect. Signed-off-by: Matthias Kaehlcke Signed-off-by: Jessica Yu --- include/linux/module.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/module.h b/include/linux/module.h index e7bdd549e527..fe5aa3736707 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -209,7 +209,7 @@ extern void cleanup_module(void); #ifdef MODULE /* Creates an alias so file2alias.c can find device table. */ #define MODULE_DEVICE_TABLE(type, name) \ -extern const typeof(name) __mod_##type##__##name##_device_table \ +extern typeof(name) __mod_##type##__##name##_device_table \ __attribute__ ((unused, alias(__stringify(name)))) #else /* !MODULE */ #define MODULE_DEVICE_TABLE(type, name)