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/kernel/kallsyms.c b/kernel/kallsyms.c
index f66da02..4e2ec19 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -269,6 +269,23 @@
return NULL;
}
+int lookup_symbol_name(unsigned long addr, char *symname)
+{
+ symname[0] = '\0';
+ symname[KSYM_NAME_LEN] = '\0';
+
+ if (is_ksym_addr(addr)) {
+ unsigned long pos;
+
+ pos = get_symbol_pos(addr, NULL, NULL);
+ /* Grab name */
+ kallsyms_expand_symbol(get_symbol_offset(pos), symname);
+ return 0;
+ }
+ /* see if it's in a module */
+ return lookup_module_symbol_name(addr, symname);
+}
+
/* Look up a kernel symbol and return it in a text buffer. */
int sprint_symbol(char *buffer, unsigned long address)
{