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Fix race between rmmod and cat /proc/kallsyms

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module_get_kallsym() leaks "struct module *" outside of module_mutex which is
no-no, because module can dissapear right after mutex unlock.

Copy all needed information from inside module_mutex into caller-supplied
space.

[bunk@stusta.de: is_exported() can now become static]
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2007-05-08 00:28:39 -07:00 committed by Linus Torvalds
parent ae84e32470
commit ea07890a68
3 changed files with 29 additions and 34 deletions
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21
include/linux/module.h
View File

@ -370,16 +370,14 @@ struct module *module_text_address(unsigned long addr);
struct module *__module_text_address(unsigned long addr);
int is_module_address(unsigned long addr);
/* Returns module and fills in value, defined and namebuf, or NULL if
/* Returns 0 and fills in value, defined and namebuf, or -ERANGE if
symnum out of range. */
struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name);
int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *name, char *module_name, int *exported);
/* Look for this name: can be of form module:name. */
unsigned long module_kallsyms_lookup_name(const char *name);
int is_exported(const char *name, const struct module *mod);
extern void __module_put_and_exit(struct module *mod, long code)
__attribute__((noreturn));
#define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
@ -527,11 +525,11 @@ static inline const char *module_address_lookup(unsigned long addr,
return NULL;
}
static inline struct module *module_get_kallsym(unsigned int symnum,
unsigned long *value,
char *type, char *name)
static inline int module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name,
char *module_name, int *exported)
{
return NULL;
return -ERANGE;
}
static inline unsigned long module_kallsyms_lookup_name(const char *name)
@ -539,11 +537,6 @@ static inline unsigned long module_kallsyms_lookup_name(const char *name)
return 0;
}
static inline int is_exported(const char *name, const struct module *mod)
{
return 0;
}
static inline int register_module_notifier(struct notifier_block * nb)
{
/* no events will happen anyway, so this can always succeed */

30
kernel/kallsyms.c
View File

@ -301,25 +301,20 @@ void __print_symbol(const char *fmt, unsigned long address)
struct kallsym_iter
{
loff_t pos;
struct module *owner;
unsigned long value;
unsigned int nameoff; /* If iterating in core kernel symbols */
char type;
char name[KSYM_NAME_LEN+1];
char module_name[MODULE_NAME_LEN + 1];
int exported;
};
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);
if (iter->owner == NULL)
if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
&iter->type, iter->name, iter->module_name,
&iter->exported) < 0)
return 0;
/* Label it "global" if it is exported, "local" if not exported. */
iter->type = is_exported(iter->name, iter->owner)
? toupper(iter->type) : tolower(iter->type);
return 1;
}
@ -328,7 +323,7 @@ static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
{
unsigned off = iter->nameoff;
iter->owner = NULL;
iter->module_name[0] = '\0';
iter->value = kallsyms_addresses[iter->pos];
iter->type = kallsyms_get_symbol_type(off);
@ -392,12 +387,17 @@ static int s_show(struct seq_file *m, void *p)
if (!iter->name[0])
return 0;
if (iter->owner)
if (iter->module_name[0]) {
char type;
/* Label it "global" if it is exported,
* "local" if not exported. */
type = iter->exported ? toupper(iter->type) :
tolower(iter->type);
seq_printf(m, "%0*lx %c %s\t[%s]\n",
(int)(2*sizeof(void*)),
iter->value, iter->type, iter->name,
module_name(iter->owner));
else
iter->value, type, iter->name, iter->module_name);
} else
seq_printf(m, "%0*lx %c %s\n",
(int)(2*sizeof(void*)),
iter->value, iter->type, iter->name);

12
kernel/module.c
View File

@ -1472,7 +1472,7 @@ static void setup_modinfo(struct module *mod, Elf_Shdr *sechdrs,
}
#ifdef CONFIG_KALLSYMS
int is_exported(const char *name, const struct module *mod)
static int is_exported(const char *name, const struct module *mod)
{
if (!mod && lookup_symbol(name, __start___ksymtab, __stop___ksymtab))
return 1;
@ -2124,8 +2124,8 @@ const char *module_address_lookup(unsigned long addr,
return NULL;
}
struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name)
int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *name, char *module_name, int *exported)
{
struct module *mod;
@ -2136,13 +2136,15 @@ struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
*type = mod->symtab[symnum].st_info;
strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
KSYM_NAME_LEN + 1);
strlcpy(module_name, mod->name, MODULE_NAME_LEN + 1);
*exported = is_exported(name, mod);
mutex_unlock(&module_mutex);
return mod;
return 0;
}
symnum -= mod->num_symtab;
}
mutex_unlock(&module_mutex);
return NULL;
return -ERANGE;
}
static unsigned long mod_find_symname(struct module *mod, const char *name)