On Thu, Mar 30, 2023 at 07:57:31PM -0500, David Vernet wrote: > kernel/bpf/helpers.c | 11 ++- > kernel/bpf/verifier.c | 1 + > .../selftests/bpf/prog_tests/task_kfunc.c | 2 + > .../selftests/bpf/progs/task_kfunc_common.h | 5 + > .../selftests/bpf/progs/task_kfunc_failure.c | 98 +++++++++++++++++-- > .../selftests/bpf/progs/task_kfunc_success.c | 52 +++++++++- > 6 files changed, 153 insertions(+), 16 deletions(-) See CI failures on gcc compiled kernel: https://github.com/kernel-patches/bpf/actions/runs/4570493668/jobs/8068004031 > __bpf_kfunc struct task_struct *bpf_task_acquire(struct task_struct *p) > { > - return get_task_struct(p); > + if (refcount_inc_not_zero(&p->rcu_users)) > + return p; > + return NULL; > } I wonder whether we should add a bit of safety net here. Like do not allow acquire of tasks with PF_KTHREAD | PF_EXITING or at least is_idle_task ?
