Skip to main content

Browse the archive

Revision 9c1c2b35f1d94de8325344c2777d7ee67492db3b authored by Jeff Layton on 03 April 2019, 17:16:01 UTC, committed by Ilya Dryomov on 21 January 2020, 18:02:37 UTC 
ceph: hold extra reference to r_parent over life of request
 
Currently, we just assume that it will stick around by virtue of the
submitter's reference, but later patches will allow the syscall to
return early and we can't rely on that reference at that point.

While I'm not aware of any reports of it, Xiubo pointed out that this
may fix a use-after-free.  If the wait for a reply times out or is
canceled via signal, and then the reply comes in after the syscall
returns, the client can end up trying to access r_parent without a
reference.

Take an extra reference to the inode when setting r_parent and release
it when releasing the request.

Cc: stable@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
1 parent def9d27
Raw File
br_nf_core.c 
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Handle firewalling core
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *	Bart De Schuymer		<bdschuym@pandora.be>
 *
 *	Lennert dedicates this file to Kerstin Wurdinger.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/in_route.h>
#include <linux/inetdevice.h>
#include <net/route.h>

#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
			     struct sk_buff *skb, u32 mtu,
			     bool confirm_neigh)
{
}

static void fake_redirect(struct dst_entry *dst, struct sock *sk,
			  struct sk_buff *skb)
{
}

static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
{
	return NULL;
}

static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst,
					   struct sk_buff *skb,
					   const void *daddr)
{
	return NULL;
}

static unsigned int fake_mtu(const struct dst_entry *dst)
{
	return dst->dev->mtu;
}

static struct dst_ops fake_dst_ops = {
	.family		= AF_INET,
	.update_pmtu	= fake_update_pmtu,
	.redirect	= fake_redirect,
	.cow_metrics	= fake_cow_metrics,
	.neigh_lookup	= fake_neigh_lookup,
	.mtu		= fake_mtu,
};

/*
 * Initialize bogus route table used to keep netfilter happy.
 * Currently, we fill in the PMTU entry because netfilter
 * refragmentation needs it, and the rt_flags entry because
 * ipt_REJECT needs it.  Future netfilter modules might
 * require us to fill additional fields.
 */
static const u32 br_dst_default_metrics[RTAX_MAX] = {
	[RTAX_MTU - 1] = 1500,
};

void br_netfilter_rtable_init(struct net_bridge *br)
{
	struct rtable *rt = &br->fake_rtable;

	atomic_set(&rt->dst.__refcnt, 1);
	rt->dst.dev = br->dev;
	dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
	rt->dst.flags	= DST_NOXFRM | DST_FAKE_RTABLE;
	rt->dst.ops = &fake_dst_ops;
}

int __init br_nf_core_init(void)
{
	return dst_entries_init(&fake_dst_ops);
}

void br_nf_core_fini(void)
{
	dst_entries_destroy(&fake_dst_ops);
}
back to top