module: make module_address_lookup safe

module_address_lookup releases preemption then returns a pointer into
the module space.  The only user (kallsyms) copies the result, so just
do that under the preempt disable.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 13 insertions, 9 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index c97bdb7eb957..aedc06be1de8 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -446,11 +446,14 @@ static inline void __module_get(struct module *module)
         __mod ? __mod->name : "kernel";         \
 })
 
-/* For kallsyms to ask for address resolution.  NULL means not found. */
-const char *module_address_lookup(unsigned long addr,
-                                  unsigned long *symbolsize,
-                                  unsigned long *offset,
-                                  char **modname);
+/* For kallsyms to ask for address resolution.  namebuf should be at
+ * least KSYM_NAME_LEN long: a pointer to namebuf is returned if
+ * found, otherwise NULL. */
+char *module_address_lookup(unsigned long addr,
+                            unsigned long *symbolsize,
+                            unsigned long *offset,
+                            char **modname,
+                            char *namebuf);
 int lookup_module_symbol_name(unsigned long addr, char *symname);
 int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);
 
@@ -516,10 +519,11 @@ static inline void module_put(struct module *module)
 #define module_name(mod) "kernel"
 
 /* For kallsyms to ask for address resolution.  NULL means not found. */
-static inline const char *module_address_lookup(unsigned long addr,
-                                                unsigned long *symbolsize,
-                                                unsigned long *offset,
-                                                char **modname)
+static inline char *module_address_lookup(unsigned long addr,
+                                          unsigned long *symbolsize,
+                                          unsigned long *offset,
+                                          char **modname,
+                                          char *namebuf)
 {
         return NULL;
 }