syzbot ([1]) reported a rcu warning for syscall program when bpf_get_current_cgroup_id() is called in the program. The bpf_get_current_cgroup_id() helper expects cgroup related mutex or rcu_read_lock(). The sleepable program cannot be protected with rcu read_lock, hence the warning. To fix the problem, Patch 1 added rcu_read_lock() in affected helpers, and Patch 2 added missing bpf_read_lock_trace() for syscall type of bpf programs. [1] https://lore.kernel.org/bpf/0000000000006d5cab05c7d9bb87@xxxxxxxxxx/ Changelog: v2 -> v3: - use rcu_read_lock() protection for bpf_get_current_[ancestor_]cgroup_id() helper. v1 -> v2: - use bpf_read_lock_trace() instead of bpf_read_lock() for bpf_prog_run_pin_on_cpu(). - disallow bpf_get_current_[ancestor_]cgroup_id() helper. Yonghong Song (2): bpf: add rcu read_lock in bpf_get_current_[ancestor_]cgroup_id() helpers bpf: add missing bpf_read_[un]lock_trace() for syscall program kernel/bpf/helpers.c | 12 ++++++++++-- net/bpf/test_run.c | 4 ++++ 2 files changed, 14 insertions(+), 2 deletions(-) -- 2.30.2
