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>
diff --git a/kernel/module.c b/kernel/module.c
index 12067ff..e814cd7 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2230,14 +2230,13 @@
return mod->strtab + mod->symtab[best].st_name;
}
-/* For kallsyms to ask for address resolution. NULL means not found.
- We don't lock, as this is used for oops resolution and races are a
- lesser concern. */
-/* FIXME: Risky: returns a pointer into a module w/o lock */
-const char *module_address_lookup(unsigned long addr,
- unsigned long *size,
- unsigned long *offset,
- char **modname)
+/* For kallsyms to ask for address resolution. NULL means not found. Careful
+ * not to lock to avoid deadlock on oopses, simply disable preemption. */
+char *module_address_lookup(unsigned long addr,
+ unsigned long *size,
+ unsigned long *offset,
+ char **modname,
+ char *namebuf)
{
struct module *mod;
const char *ret = NULL;
@@ -2252,8 +2251,13 @@
break;
}
}
+ /* Make a copy in here where it's safe */
+ if (ret) {
+ strncpy(namebuf, ret, KSYM_NAME_LEN - 1);
+ ret = namebuf;
+ }
preempt_enable();
- return ret;
+ return (char *)ret;
}
int lookup_module_symbol_name(unsigned long addr, char *symname)