From 50aadd07363cb1e6f0e46c34056b2ca1617b1b0c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 19 Feb 2025 17:14:17 +0100 Subject: [PATCH] yama: don't abuse rcu_read_lock/get_task_struct in yama_task_prctl() current->group_leader is stable, no need to take rcu_read_lock() and do get/put_task_struct(). Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20250219161417.GA20851@redhat.com Signed-off-by: Kees Cook --- security/yama/yama_lsm.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 1971710620c18..3d064dd4e03f9 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -222,7 +222,7 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) { int rc = -ENOSYS; - struct task_struct *myself = current; + struct task_struct *myself; switch (option) { case PR_SET_PTRACER: @@ -232,11 +232,7 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, * leader checking is handled later when walking the ancestry * at the time of PTRACE_ATTACH check. */ - rcu_read_lock(); - if (!thread_group_leader(myself)) - myself = rcu_dereference(myself->group_leader); - get_task_struct(myself); - rcu_read_unlock(); + myself = current->group_leader; if (arg2 == 0) { yama_ptracer_del(NULL, myself); @@ -255,7 +251,6 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, } } - put_task_struct(myself); break; }