| Message ID | 20190525185753.2467090-1-yhs@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next] bpf: check signal validity in nmi for bpf_send_signal() helper | expand |
On 05/25/2019 08:57 PM, Yonghong Song wrote: > 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. > > Signed-off-by: Yonghong Song <yhs@fb.com> Applied, thanks!
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;
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. Signed-off-by: Yonghong Song <yhs@fb.com> --- kernel/trace/bpf_trace.c | 6 ++++++ 1 file changed, 6 insertions(+)