[PATCH 5.19 253/717] bpf: Ensure correct locking around vulnerable function find_vpid()

Greg Kroah-Hartman
2022-10-22T07:56:48Z

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 7a3444988c84..494ba88054e8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4361,7 +4361,9 @@ 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;

--
2.35.1