From: Yonghong Song Date: Sat, 25 May 2019 18:57:53 +0000 (-0700) Subject: bpf: check signal validity in nmi for bpf_send_signal() helper X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=e1afb70252a8614e1ef7aec05ff1b84fd324b782;p=openwrt%2Fstaging%2Fblogic.git bpf: check signal validity in nmi for bpf_send_signal() helper Commit 8b401f9ed244 ("bpf: implement bpf_send_signal() helper") introduced bpf_send_signal() helper. If the context is nmi, the sending signal work needs to be deferred to irq_work. If the signal is invalid, the error will appear in irq_work and it won't be propagated to user. This patch did an early check in the helper itself to notify user invalid signal, as suggested by Daniel. Suggested-by: Daniel Borkmann Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann --- diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 70029eafc71f..fe73926a07cd 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -600,6 +600,12 @@ BPF_CALL_1(bpf_send_signal, u32, sig) return -EPERM; if (in_nmi()) { + /* Do an early check on signal validity. Otherwise, + * the error is lost in deferred irq_work. + */ + if (unlikely(!valid_signal(sig))) + return -EINVAL; + work = this_cpu_ptr(&send_signal_work); if (work->irq_work.flags & IRQ_WORK_BUSY) return -EBUSY;