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bpf: Ensure correct locking around vulnerable function find_vpid() 

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: 41bdc4b40e ("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
This commit is contained in:
Lee Jones 2022-09-12 14:38:55 +01:00 committed by Daniel Borkmann
parent a37a32583e
commit 83c10cc362
1 changed files with 2 additions and 0 deletions
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2
kernel/bpf/syscall.c
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@ -4395,7 +4395,9 @@ static int bpf_task_fd_query(const union bpf_attr *attr,
if (attr->task_fd_query.flags != 0) if (attr->task_fd_query.flags != 0)
return -EINVAL; return -EINVAL;
rcu_read_lock();
task = get_pid_task(find_vpid(pid), PIDTYPE_PID); task = get_pid_task(find_vpid(pid), PIDTYPE_PID);
rcu_read_unlock();
if (!task) if (!task)
return -ENOENT; return -ENOENT;