From: Abhinav Singh <singhabhinav9051571833@gmail.com>
To: akpm@linux-foundation.org, brauner@kernel.org, surenb@google.com,
mst@redhat.com, michael.christie@oracle.com,
mathieu.desnoyers@efficios.com, mjguzik@gmail.com,
npiggin@gmail.com, shakeelb@google.com, peterz@infradead.org
Cc: Abhinav Singh <singhabhinav9051571833@gmail.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] Fixing warning of directly dereferencing __rcu tagged
Date: Thu, 26 Oct 2023 03:58:11 +0530 [thread overview]
Message-ID: <20231025222811.855336-1-singhabhinav9051571833@gmail.com> (raw)
This patch fixes the warning about directly dereferencing a pointer
tagged with __rcu annotation.
Dereferencing the pointers tagged with __rcu directly should
always be avoided according to the docs. There is a rcu helper
functions rcu_dereference(...) to use when dereferencing a __rcu
pointer. This functions returns the non __rcu tagged pointer.
Like normal pointer there should be a check for null case when
further dereferencing the returned dereferenced __rcu pointer.
Signed-off-by: Abhinav Singh <singhabhinav9051571833@gmail.com>
---
kernel/fork.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 10917c3e1f03..5afb1b389a66 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2369,7 +2369,9 @@ __latent_entropy struct task_struct *copy_process(
retval = -EAGAIN;
if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
- if (p->real_cred->user != INIT_USER &&
+ const struct cred *real_cred = rcu_dereference(p->real_cred);
+
+ if (real_cred && real_cred->user != INIT_USER &&
!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
goto bad_fork_cleanup_count;
}
--
2.39.2
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next reply other threads:[~2023-10-25 22:28 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-25 22:28 Abhinav Singh [this message]
2023-10-25 22:38 ` [PATCH] Fixing warning of directly dereferencing __rcu tagged Andrew Morton
2023-10-25 23:27 ` Abhinav Singh
2023-10-25 23:50 ` Andrew Morton
2023-10-26 12:16 ` [PATCH v2] Fixing directly deferencing a __rcu pointer warning Abhinav Singh
2023-10-26 13:14 ` Michael S. Tsirkin
2023-10-26 14:06 ` Mateusz Guzik
2023-10-26 14:51 ` Mathieu Desnoyers
2023-10-26 15:07 ` Mateusz Guzik
2023-10-26 15:17 ` Michael S. Tsirkin
2023-10-26 15:37 ` Abhinav Singh
2023-10-26 15:47 ` Michael S. Tsirkin
2023-10-27 6:37 ` [PATCH v3] " Abhinav Singh
2023-10-27 6:41 ` Abhinav Singh
2023-10-27 7:00 ` Michael S. Tsirkin
2023-10-27 6:50 ` Michael S. Tsirkin
2023-10-26 12:18 ` [PATCH] Fixing warning of directly dereferencing __rcu tagged Abhinav Singh
2023-10-26 12:27 ` [PATCH] Fixing directly deferencing a __rcu pointer warning Abhinav Singh
2023-10-26 15:03 ` Peter Zijlstra
2023-10-27 12:22 ` Oleg Nesterov
2023-10-28 10:22 ` [PATCH v3] " Abhinav Singh
2023-10-28 10:31 ` Abhinav Singh
2023-10-28 12:20 ` Michael S. Tsirkin
2023-10-28 20:43 ` Abhinav Singh
2023-10-28 20:46 ` Abhinav Singh
2023-11-03 6:30 ` kernel test robot
2023-11-12 19:30 ` [PATCH v4] " Abhinav Singh
2023-11-12 19:56 ` Mathieu Desnoyers
2023-11-12 19:58 ` Peter Zijlstra
2023-11-12 20:18 ` Abhinav Singh
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