| Message ID | 20180423170921.16162-1-guro@fb.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] bpf: disable and restore preemption in __BPF_PROG_RUN_ARRAY | expand |
On Mon, Apr 23, 2018 at 06:09:21PM +0100, Roman Gushchin wrote: > Running bpf programs requires disabled preemption, > however at least some* of the BPF_PROG_RUN_ARRAY users > do not follow this rule. > > To fix this bug, and also to make it not happen in the future, > let's add explicit preemption disabling/re-enabling > to the __BPF_PROG_RUN_ARRAY code. > > * for example: > [ 17.624472] RIP: 0010:__cgroup_bpf_run_filter_sk+0x1c4/0x1d0 > ... > [ 17.640890] inet6_create+0x3eb/0x520 > [ 17.641405] __sock_create+0x242/0x340 > [ 17.641939] __sys_socket+0x57/0xe0 > [ 17.642370] ? trace_hardirqs_off_thunk+0x1a/0x1c > [ 17.642944] SyS_socket+0xa/0x10 > [ 17.643357] do_syscall_64+0x79/0x220 > [ 17.643879] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > Signed-off-by: Roman Gushchin <guro@fb.com> > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org>
On 04/23/2018 07:09 PM, Roman Gushchin wrote: > Running bpf programs requires disabled preemption, > however at least some* of the BPF_PROG_RUN_ARRAY users > do not follow this rule. > > To fix this bug, and also to make it not happen in the future, > let's add explicit preemption disabling/re-enabling > to the __BPF_PROG_RUN_ARRAY code. > > * for example: > [ 17.624472] RIP: 0010:__cgroup_bpf_run_filter_sk+0x1c4/0x1d0 > ... > [ 17.640890] inet6_create+0x3eb/0x520 > [ 17.641405] __sock_create+0x242/0x340 > [ 17.641939] __sys_socket+0x57/0xe0 > [ 17.642370] ? trace_hardirqs_off_thunk+0x1a/0x1c > [ 17.642944] SyS_socket+0xa/0x10 > [ 17.643357] do_syscall_64+0x79/0x220 > [ 17.643879] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > Signed-off-by: Roman Gushchin <guro@fb.com> > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Daniel Borkmann <daniel@iogearbox.net> Applied to bpf, thanks Roman.
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 486e65e3db26..dc586cc64bc2 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -351,6 +351,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, struct bpf_prog **_prog, *__prog; \ struct bpf_prog_array *_array; \ u32 _ret = 1; \ + preempt_disable(); \ rcu_read_lock(); \ _array = rcu_dereference(array); \ if (unlikely(check_non_null && !_array))\ @@ -362,6 +363,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array, } \ _out: \ rcu_read_unlock(); \ + preempt_enable_no_resched(); \ _ret; \ })
Running bpf programs requires disabled preemption, however at least some* of the BPF_PROG_RUN_ARRAY users do not follow this rule. To fix this bug, and also to make it not happen in the future, let's add explicit preemption disabling/re-enabling to the __BPF_PROG_RUN_ARRAY code. * for example: [ 17.624472] RIP: 0010:__cgroup_bpf_run_filter_sk+0x1c4/0x1d0 ... [ 17.640890] inet6_create+0x3eb/0x520 [ 17.641405] __sock_create+0x242/0x340 [ 17.641939] __sys_socket+0x57/0xe0 [ 17.642370] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 17.642944] SyS_socket+0xa/0x10 [ 17.643357] do_syscall_64+0x79/0x220 [ 17.643879] entry_SYSCALL_64_after_hwframe+0x42/0xb7 Signed-off-by: Roman Gushchin <guro@fb.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> --- include/linux/bpf.h | 2 ++ 1 file changed, 2 insertions(+)