From: Lee Jones lee@kernel.org
[ Upstream commit 83c10cc362d91c0d8d25e60779ee52fdbbf3894d ]
The documentation for find_vpid() clearly states:
"Must be called with the tasklist_lock or rcu_read_lock() held."
Presently we do neither for find_vpid() instance in bpf_task_fd_query(). Add proper rcu_read_lock/unlock() to fix the issue.
Fixes: 41bdc4b40ed6f ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY") Signed-off-by: Lee Jones lee@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Yonghong Song yhs@fb.com Link: https://lore.kernel.org/bpf/20220912133855.1218900-1-lee@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/syscall.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 99ce46f51889..aea9852f1c22 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4100,7 +4100,9 @@ static int bpf_task_fd_query(const union bpf_attr *attr, if (attr->task_fd_query.flags != 0) return -EINVAL;
+ rcu_read_lock(); task = get_pid_task(find_vpid(pid), PIDTYPE_PID); + rcu_read_unlock(); if (!task) return -ENOENT;