From: Amol Grover <frextrite@gmail.com>
To: James Morris <jmorris@namei.org>, "Serge E . Hallyn" <serge@hallyn.com>
Cc: linux-kernel@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org,
Joel Fernandes <joel@joelfernandes.org>,
Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
linux-security-module@vger.kernel.org,
Amol Grover <frextrite@gmail.com>
Subject: [PATCH] device_cgroup: Fix RCU list debugging warning
Date: Sat, 22 Feb 2020 22:49:39 +0530 [thread overview]
Message-ID: <20200222171938.14339-1-frextrite@gmail.com> (raw)
exceptions may be traversed using list_for_each_entry_rcu()
outside of an RCU read side critical section BUT under the
protection of decgroup_mutex. Hence add the corresponding
lockdep expression to fix the following false-positive
warning:
[ 2.304417] =============================
[ 2.304418] WARNING: suspicious RCU usage
[ 2.304420] 5.5.4-stable #17 Tainted: G E
[ 2.304422] -----------------------------
[ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!!
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
security/device_cgroup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 7d0f8f7431ff..b7da9e0970d9 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head *exceptions, short type,
{
struct dev_exception_item *ex;
- list_for_each_entry_rcu(ex, exceptions, list) {
+ list_for_each_entry_rcu(ex, exceptions, list,
+ lockdep_is_held(&devcgroup_mutex)) {
if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
continue;
if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
--
2.24.1
reply other threads:[~2020-02-22 17:20 UTC|newest]
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