lkml.org 
[lkml]   [2018]   [Sep]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.18 152/235] bpf: fix rcu annotations in compute_effective_progs()
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Roman Gushchin <guro@fb.com>

[ Upstream commit 3960f4fd6585608e8cc285d9665821985494e147 ]

The progs local variable in compute_effective_progs() is marked
as __rcu, which is not correct. This is a local pointer, which
is initialized by bpf_prog_array_alloc(), which also now
returns a generic non-rcu pointer.

The real rcu-protected pointer is *array (array is a pointer
to an RCU-protected pointer), so the assignment should be performed
using rcu_assign_pointer().

Fixes: 324bda9e6c5a ("bpf: multi program support for cgroup+bpf")
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/bpf/cgroup.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -95,7 +95,7 @@ static int compute_effective_progs(struc
enum bpf_attach_type type,
struct bpf_prog_array __rcu **array)
{
- struct bpf_prog_array __rcu *progs;
+ struct bpf_prog_array *progs;
struct bpf_prog_list *pl;
struct cgroup *p = cgrp;
int cnt = 0;
@@ -120,13 +120,12 @@ static int compute_effective_progs(struc
&p->bpf.progs[type], node) {
if (!pl->prog)
continue;
- rcu_dereference_protected(progs, 1)->
- progs[cnt++] = pl->prog;
+ progs->progs[cnt++] = pl->prog;
}
p = cgroup_parent(p);
} while (p);

- *array = progs;
+ rcu_assign_pointer(*array, progs);
return 0;
}


\
 
 \ /
  Last update: 2018-09-24 14:50    [W:0.852 / U:3.196 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site