Commit 2a086e5d authored Apr 03, 2011 by Tetsuo Handa Committed by James Morris Apr 19, 2011

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>

parent a3232d2f

security/tomoyo/common.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -459,8 +459,16 @@ static int tomoyo_write_profile(struct tomoyo_io_buffer *head)
		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;
		}

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