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authorDavide Caratti <dcaratti@redhat.com>2021-04-28 16:23:07 +0300
committerDavid S. Miller <davem@davemloft.net>2021-04-30 01:31:53 +0300
commit7c0ea5930c1c211931819d83cfb157bff1539a4c (patch)
treec55d9c3788904b0387721b94ac0eacddaa7cf10a
parent94604548aa7163fa14b837149bb0cb708bc613bc (diff)
downloadlinux-7c0ea5930c1c211931819d83cfb157bff1539a4c.tar.xz
openvswitch: fix stack OOB read while fragmenting IPv4 packets
running openvswitch on kernels built with KASAN, it's possible to see the following splat while testing fragmentation of IPv4 packets: BUG: KASAN: stack-out-of-bounds in ip_do_fragment+0x1b03/0x1f60 Read of size 1 at addr ffff888112fc713c by task handler2/1367 CPU: 0 PID: 1367 Comm: handler2 Not tainted 5.12.0-rc6+ #418 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014 Call Trace: dump_stack+0x92/0xc1 print_address_description.constprop.7+0x1a/0x150 kasan_report.cold.13+0x7f/0x111 ip_do_fragment+0x1b03/0x1f60 ovs_fragment+0x5bf/0x840 [openvswitch] do_execute_actions+0x1bd5/0x2400 [openvswitch] ovs_execute_actions+0xc8/0x3d0 [openvswitch] ovs_packet_cmd_execute+0xa39/0x1150 [openvswitch] genl_family_rcv_msg_doit.isra.15+0x227/0x2d0 genl_rcv_msg+0x287/0x490 netlink_rcv_skb+0x120/0x380 genl_rcv+0x24/0x40 netlink_unicast+0x439/0x630 netlink_sendmsg+0x719/0xbf0 sock_sendmsg+0xe2/0x110 ____sys_sendmsg+0x5ba/0x890 ___sys_sendmsg+0xe9/0x160 __sys_sendmsg+0xd3/0x170 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f957079db07 Code: c3 66 90 41 54 41 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 eb ec ff ff 44 89 e2 48 89 ee 89 df 41 89 c0 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 48 89 44 24 08 e8 24 ed ff ff 48 RSP: 002b:00007f956ce35a50 EFLAGS: 00000293 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007f957079db07 RDX: 0000000000000000 RSI: 00007f956ce35ae0 RDI: 0000000000000019 RBP: 00007f956ce35ae0 R08: 0000000000000000 R09: 00007f9558006730 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f956ce37308 R14: 00007f956ce35f80 R15: 00007f956ce35ae0 The buggy address belongs to the page: page:00000000af2a1d93 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112fc7 flags: 0x17ffffc0000000() raw: 0017ffffc0000000 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected addr ffff888112fc713c is located in stack of task handler2/1367 at offset 180 in frame: ovs_fragment+0x0/0x840 [openvswitch] this frame has 2 objects: [32, 144) 'ovs_dst' [192, 424) 'ovs_rt' Memory state around the buggy address: ffff888112fc7000: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7080: 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00 >ffff888112fc7100: 00 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 ^ ffff888112fc7180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7200: 00 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00 for IPv4 packets, ovs_fragment() uses a temporary struct dst_entry. Then, in the following call graph: ip_do_fragment() ip_skb_dst_mtu() ip_dst_mtu_maybe_forward() ip_mtu_locked() the pointer to struct dst_entry is used as pointer to struct rtable: this turns the access to struct members like rt_mtu_locked into an OOB read in the stack. Fix this changing the temporary variable used for IPv4 packets in ovs_fragment(), similarly to what is done for IPv6 few lines below. Fixes: d52e5a7e7ca4 ("ipv4: lock mtu in fnhe when received PMTU < net.ipv4.route.min_pmt") Cc: <stable@vger.kernel.org> Acked-by: Eelco Chaudron <echaudro@redhat.com> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/openvswitch/actions.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 92a0b67b2728..77d924ab8cdb 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -827,17 +827,17 @@ static void ovs_fragment(struct net *net, struct vport *vport,
}
if (key->eth.type == htons(ETH_P_IP)) {
- struct dst_entry ovs_dst;
+ struct rtable ovs_rt = { 0 };
unsigned long orig_dst;
prepare_frag(vport, skb, orig_network_offset,
ovs_key_mac_proto(key));
- dst_init(&ovs_dst, &ovs_dst_ops, NULL, 1,
+ dst_init(&ovs_rt.dst, &ovs_dst_ops, NULL, 1,
DST_OBSOLETE_NONE, DST_NOCOUNT);
- ovs_dst.dev = vport->dev;
+ ovs_rt.dst.dev = vport->dev;
orig_dst = skb->_skb_refdst;
- skb_dst_set_noref(skb, &ovs_dst);
+ skb_dst_set_noref(skb, &ovs_rt.dst);
IPCB(skb)->frag_max_size = mru;
ip_do_fragment(net, skb->sk, skb, ovs_vport_output);