Fix race between cat /proc/*/wchan and rmmod et al
kallsyms_lookup() can go iterating over modules list unprotected which is OK
for emergency situations (oops), but not OK for regular stuff like
/proc/*/wchan.
Introduce lookup_symbol_name()/lookup_module_symbol_name() which copy symbol
name into caller-supplied buffer or return -ERANGE. All copying is done with
module_mutex held, so...
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 3e3b92d..ae0117a 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -30,6 +30,8 @@
/* Look up a kernel symbol and print it to the kernel messages. */
extern void __print_symbol(const char *fmt, unsigned long address);
+int lookup_symbol_name(unsigned long addr, char *symname);
+
#else /* !CONFIG_KALLSYMS */
static inline unsigned long kallsyms_lookup_name(const char *name)
@@ -58,6 +60,11 @@
return 0;
}
+static inline int lookup_symbol_name(unsigned long addr, char *symname)
+{
+ return -ERANGE;
+}
+
/* Stupid that this does nothing, but I didn't create this mess. */
#define __print_symbol(fmt, addr)
#endif /*CONFIG_KALLSYMS*/
diff --git a/include/linux/module.h b/include/linux/module.h
index 58d5a10..099ae59 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -454,6 +454,7 @@
unsigned long *symbolsize,
unsigned long *offset,
char **modname);
+int lookup_module_symbol_name(unsigned long addr, char *symname);
/* For extable.c to search modules' exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr);
@@ -525,6 +526,11 @@
return NULL;
}
+static inline int lookup_module_symbol_name(unsigned long addr, char *symname)
+{
+ return -ERANGE;
+}
+
static inline int module_get_kallsym(unsigned int symnum, unsigned long *value,
char *type, char *name,
char *module_name, int *exported)