From 6899b32b5b2dee358936b82b8363b716607a138f Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Mon, 23 Apr 2018 18:09:21 +0100 Subject: [PATCH] bpf: disable and restore preemption in __BPF_PROG_RUN_ARRAY 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 Cc: Alexei Starovoitov Cc: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- include/linux/bpf.h | 2 ++ 1 file changed, 2 insertions(+) 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; \ }) -- 2.20.1