Messages in this thread Patch in this message | | | From | Abhinav Singh <> | Subject | [PATCH] Fixing warning of directly dereferencing __rcu tagged | Date | Thu, 26 Oct 2023 03:58:11 +0530 |
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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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