[PATCH] null-terminate over-long /proc/kallsyms symbols

Got a customer bug report (https://bugzilla.novell.com/190296) about kernel
symbols longer than 127 characters which end up in a string buffer that is
not NULL terminated, leading to garbage in /proc/kallsyms.  Using strlcpy
prevents this from happening, even though such symbols still won't come out
right.

A better fix would be to not use a fixed-size buffer, but it's probably not
worth the trouble.  (Modversion'ed symbols even have a length limit of 60.)

[bunk@stusta.de: build fix]
Signed-off-by: NAndreas Gruenbacher <agruen@suse.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/module.h

@@ -362,10 +362,8 @@ int is_module_address(unsigned long addr);
 
 /* Returns module and fills in value, defined and namebuf, or NULL if
    symnum out of range. */
-struct module *module_get_kallsym(unsigned int symnum,
-				  unsigned long *value,
-				  char *type,
-				  char namebuf[128]);
+struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
+				char *type, char *name, size_t namelen);
 
 /* Look for this name: can be of form module:name. */
 unsigned long module_kallsyms_lookup_name(const char *name);
@@ -535,8 +533,8 @@ static inline const char *module_address_lookup(unsigned long addr,
 
 static inline struct module *module_get_kallsym(unsigned int symnum,
 						unsigned long *value,
-						char *type,
-						char namebuf[128])
+						char *type, char *name,
+						size_t namelen)
 {
 	return NULL;
 }

kernel/kallsyms.c

@@ -275,8 +275,8 @@ static void upcase_if_global(struct kallsym_iter *iter)
 static int get_ksymbol_mod(struct kallsym_iter *iter)
 {
 	iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
-					 &iter->value,
-					 &iter->type, iter->name);
+					 &iter->value, &iter->type,
+					 iter->name, sizeof(iter->name));
 	if (iter->owner == NULL)
 		return 0;
 

kernel/module.c

@@ -2019,10 +2019,8 @@ const char *module_address_lookup(unsigned long addr,
 	return NULL;
 }
 
-struct module *module_get_kallsym(unsigned int symnum,
-				  unsigned long *value,
-				  char *type,
-				  char namebuf[128])
+struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
+				char *type, char *name, size_t namelen)
 {
 	struct module *mod;
 
@@ -2031,9 +2029,8 @@ struct module *module_get_kallsym(unsigned int symnum,
 		if (symnum < mod->num_symtab) {
 			*value = mod->symtab[symnum].st_value;
 			*type = mod->symtab[symnum].st_info;
-			strncpy(namebuf,
-				mod->strtab + mod->symtab[symnum].st_name,
-				127);
+			strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
+				namelen);
 			mutex_unlock(&module_mutex);
 			return mod;
 		}