TOMOYO: Fix race on updating profile's comment line.
In tomoyo_write_profile() since 2.6.34, a lock was by error missing when
replacing profile's comment line. If multiple threads attempted
echo '0-COMMENT=comment' > /sys/kernel/security/tomoyo/profile
in parallel, garbage collector will fail to kfree() the old value.
Protect the replacement using a lock. Also, keep the old value rather than
replace with empty string when out of memory error has occurred.
Signed-off-by: Xiaochen Wang <wangxiaochen0@gmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 7556315..2b7b1a1 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -459,8 +459,16 @@
if (profile == &tomoyo_default_profile)
return -EINVAL;
if (!strcmp(data, "COMMENT")) {
- const struct tomoyo_path_info *old_comment = profile->comment;
- profile->comment = tomoyo_get_name(cp);
+ static DEFINE_SPINLOCK(lock);
+ const struct tomoyo_path_info *new_comment
+ = tomoyo_get_name(cp);
+ const struct tomoyo_path_info *old_comment;
+ if (!new_comment)
+ return -ENOMEM;
+ spin_lock(&lock);
+ old_comment = profile->comment;
+ profile->comment = new_comment;
+ spin_unlock(&lock);
tomoyo_put_name(old_comment);
return 0;
}