[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: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 10 insertions, 15 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index d06c74fb8c26..0dfb794c52d3 100644
--- a/include/linux/module.h
+++ b/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;
 }
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 39277dd6bf90..ab16a5a4cfe9 100644
--- a/kernel/kallsyms.c
+++ b/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;
 
diff --git a/kernel/module.c b/kernel/module.c
index 35e1b1f859d7..2a19cd47c046 100644
--- a/kernel/module.c
+++ b/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;
                 }