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Commit c7018495 authored by Xiyu Yang's avatar Xiyu Yang Committed by Greg Kroah-Hartman
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apparmor: Fix aa_label refcnt leak in policy_update 



commit c6b39f070722ea9963ffe756bfe94e89218c5e63 upstream.

policy_update() invokes begin_current_label_crit_section(), which
returns a reference of the updated aa_label object to "label" with
increased refcount.

When policy_update() returns, "label" becomes invalid, so the refcount
should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
policy_update(). When aa_may_manage_policy() returns not NULL, the
refcnt increased by begin_current_label_crit_section() is not decreased,
causing a refcnt leak.

Fix this issue by jumping to "end_section" label when
aa_may_manage_policy() returns not NULL.

Fixes: 5ac8c355 ("apparmor: allow introspecting the loaded policy pre internal transform")
Signed-off-by: default avatarXiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: default avatarXin Tan <tanxin.ctf@gmail.com>
Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dd73adb1

security/apparmor/apparmorfs.c

+2 −1
Original line number Diff line number Diff line
@@ -424,7 +424,7 @@ static ssize_t policy_update(u32 mask, const char __user *buf, size_t size, 
	 */

	error = aa_may_manage_policy(label, ns, mask);

	if (error)

		return error;

		goto end_section;



	data = aa_simple_write_to_buffer(buf, size, size, pos);

	error = PTR_ERR(data);
@@ -432,6 +432,7 @@ static ssize_t policy_update(u32 mask, const char __user *buf, size_t size, 
		error = aa_replace_profiles(ns, label, mask, data);

		aa_put_loaddata(data);

	}

end_section:

	end_current_label_crit_section(label);



	return error;