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Message-ID: <1565953224-104941-1-git-send-email-yangyingliang@huawei.com>
Date: Fri, 16 Aug 2019 19:00:24 +0800
From: Yang Yingliang <yangyingliang@...wei.com>
To: <netdev@...r.kernel.org>
CC: <jasowang@...hat.com>, <eric.dumazet@...il.com>,
<xiyou.wangcong@...il.com>, <davem@...emloft.net>,
<yangyingliang@...wei.com>, <weiyongjun1@...wei.com>
Subject: [PATCH v2] tun: fix use-after-free when register netdev failed
I got a UAF repport in tun driver when doing fuzzy test:
[ 466.269490] ==================================================================
[ 466.271792] BUG: KASAN: use-after-free in tun_chr_read_iter+0x2ca/0x2d0
[ 466.271806] Read of size 8 at addr ffff888372139250 by task tun-test/2699
[ 466.271810]
[ 466.271824] CPU: 1 PID: 2699 Comm: tun-test Not tainted 5.3.0-rc1-00001-g5a9433db2614-dirty #427
[ 466.271833] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 466.271838] Call Trace:
[ 466.271858] dump_stack+0xca/0x13e
[ 466.271871] ? tun_chr_read_iter+0x2ca/0x2d0
[ 466.271890] print_address_description+0x79/0x440
[ 466.271906] ? vprintk_func+0x5e/0xf0
[ 466.271920] ? tun_chr_read_iter+0x2ca/0x2d0
[ 466.271935] __kasan_report+0x15c/0x1df
[ 466.271958] ? tun_chr_read_iter+0x2ca/0x2d0
[ 466.271976] kasan_report+0xe/0x20
[ 466.271987] tun_chr_read_iter+0x2ca/0x2d0
[ 466.272013] do_iter_readv_writev+0x4b7/0x740
[ 466.272032] ? default_llseek+0x2d0/0x2d0
[ 466.272072] do_iter_read+0x1c5/0x5e0
[ 466.272110] vfs_readv+0x108/0x180
[ 466.299007] ? compat_rw_copy_check_uvector+0x440/0x440
[ 466.299020] ? fsnotify+0x888/0xd50
[ 466.299040] ? __fsnotify_parent+0xd0/0x350
[ 466.299064] ? fsnotify_first_mark+0x1e0/0x1e0
[ 466.304548] ? vfs_write+0x264/0x510
[ 466.304569] ? ksys_write+0x101/0x210
[ 466.304591] ? do_preadv+0x116/0x1a0
[ 466.304609] do_preadv+0x116/0x1a0
[ 466.309829] do_syscall_64+0xc8/0x600
[ 466.309849] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 466.309861] RIP: 0033:0x4560f9
[ 466.309875] Code: 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
[ 466.309889] RSP: 002b:00007ffffa5166e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000127
[ 466.322992] RAX: ffffffffffffffda RBX: 0000000000400460 RCX: 00000000004560f9
[ 466.322999] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003
[ 466.323007] RBP: 00007ffffa516700 R08: 0000000000000004 R09: 0000000000000000
[ 466.323014] R10: 0000000000000000 R11: 0000000000000206 R12: 000000000040cb10
[ 466.323021] R13: 0000000000000000 R14: 00000000006d7018 R15: 0000000000000000
[ 466.323057]
[ 466.323064] Allocated by task 2605:
[ 466.335165] save_stack+0x19/0x80
[ 466.336240] __kasan_kmalloc.constprop.8+0xa0/0xd0
[ 466.337755] kmem_cache_alloc+0xe8/0x320
[ 466.339050] getname_flags+0xca/0x560
[ 466.340229] user_path_at_empty+0x2c/0x50
[ 466.341508] vfs_statx+0xe6/0x190
[ 466.342619] __do_sys_newstat+0x81/0x100
[ 466.343908] do_syscall_64+0xc8/0x600
[ 466.345303] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 466.347034]
[ 466.347517] Freed by task 2605:
[ 466.348471] save_stack+0x19/0x80
[ 466.349476] __kasan_slab_free+0x12e/0x180
[ 466.350726] kmem_cache_free+0xc8/0x430
[ 466.351874] putname+0xe2/0x120
[ 466.352921] filename_lookup+0x257/0x3e0
[ 466.354319] vfs_statx+0xe6/0x190
[ 466.355498] __do_sys_newstat+0x81/0x100
[ 466.356889] do_syscall_64+0xc8/0x600
[ 466.358037] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 466.359567]
[ 466.360050] The buggy address belongs to the object at ffff888372139100
[ 466.360050] which belongs to the cache names_cache of size 4096
[ 466.363735] The buggy address is located 336 bytes inside of
[ 466.363735] 4096-byte region [ffff888372139100, ffff88837213a100)
[ 466.367179] The buggy address belongs to the page:
[ 466.368604] page:ffffea000dc84e00 refcount:1 mapcount:0 mapping:ffff8883df1b4f00 index:0x0 compound_mapcount: 0
[ 466.371582] flags: 0x2fffff80010200(slab|head)
[ 466.372910] raw: 002fffff80010200 dead000000000100 dead000000000122 ffff8883df1b4f00
[ 466.375209] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
[ 466.377778] page dumped because: kasan: bad access detected
[ 466.379730]
[ 466.380288] Memory state around the buggy address:
[ 466.381844] ffff888372139100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 466.384009] ffff888372139180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 466.386131] >ffff888372139200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 466.388257] ^
[ 466.390234] ffff888372139280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 466.392512] ffff888372139300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 466.394667] ==================================================================
tun_chr_read_iter() accessed the memory which freed by free_netdev()
called by tun_set_iff():
CPUA CPUB
tun_set_iff()
alloc_netdev_mqs()
tun_attach()
tun_chr_read_iter()
tun_get()
register_netdevice() <-- inject error
tun_detach_all()
synchronize_net()
tun_do_read()
tun_ring_recv()
schedule()
free_netdev()
netdev_freemem()
tun_put()
dev_put() <-- UAF
Move tun_set_real_num_queues() out of tun_attach() and call it
before register_netdevice() in tun_set_iff().
Call tun_attach() after register_netdevice() to make sure tfile->tun
is not published until the netdevice is registered. So the read/write
thread can not use the tun pointer that may freed by free_netdev().
(The tun and dev pointer are allocated by alloc_netdev_mqs(), they can
be freed by netdev_freemem().)
---
Changes in v2:
- add a param in tun_set_real_num_queues()
- move tun_set_real_num_queues() out of tun_attach()
- call tun_set_real_num_queues() before register_netdevice()
- call tun_attach() after register_netdevice()
---
Cc: Yang Yingliang <yangyingliang@...wei.com>
Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice")
Reported-by: Hulk Robot <hulkci@...wei.com>
Suggested-by: Jason Wang <jasowang@...hat.com>
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
drivers/net/tun.c | 38 +++++++++++++++++++++-----------------
1 file changed, 21 insertions(+), 17 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index db16d7a13e00..a19f864c5f8d 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -626,10 +626,11 @@ static inline bool tun_not_capable(struct tun_struct *tun)
!ns_capable(net->user_ns, CAP_NET_ADMIN);
}
-static void tun_set_real_num_queues(struct tun_struct *tun)
+static void tun_set_real_num_queues(struct tun_struct *tun,
+ unsigned int numqueues)
{
- netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
- netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
+ netif_set_real_num_tx_queues(tun->dev, numqueues);
+ netif_set_real_num_rx_queues(tun->dev, numqueues);
}
static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
@@ -708,7 +709,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
tun_flow_delete_by_queue(tun, tun->numqueues + 1);
/* Drop read queue */
tun_queue_purge(tfile);
- tun_set_real_num_queues(tun);
+ tun_set_real_num_queues(tun, tun->numqueues);
} else if (tfile->detached && clean) {
tun = tun_enable_queue(tfile);
sock_put(&tfile->sk);
@@ -873,7 +874,6 @@ static int tun_attach(struct tun_struct *tun, struct file *file,
rcu_assign_pointer(tfile->tun, tun);
rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
tun->numqueues++;
- tun_set_real_num_queues(tun);
out:
return err;
}
@@ -2734,6 +2734,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
if (err < 0)
return err;
+ tun_set_real_num_queues(tun, tun->numqueues);
+
if (tun->flags & IFF_MULTI_QUEUE &&
(tun->numqueues + tun->numdisabled > 1)) {
/* One or more queue has already been attached, no need
@@ -2828,14 +2830,18 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
(ifr->ifr_flags & TUN_FEATURES);
INIT_LIST_HEAD(&tun->disabled);
- err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI,
- ifr->ifr_flags & IFF_NAPI_FRAGS);
- if (err < 0)
- goto err_free_flow;
+
+ tun_set_real_num_queues(tun, tun->numqueues + 1);
err = register_netdevice(tun->dev);
if (err < 0)
- goto err_detach;
+ /* register_netdevice() already called tun_free_netdev() */
+ goto err_free_dev;
+
+ err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI,
+ ifr->ifr_flags & IFF_NAPI_FRAGS);
+ if (err < 0)
+ goto err_unregister;
}
netif_carrier_on(tun->dev);
@@ -2851,14 +2857,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
strcpy(ifr->ifr_name, tun->dev->name);
return 0;
-err_detach:
- tun_detach_all(dev);
- /* register_netdevice() already called tun_free_netdev() */
- goto err_free_dev;
+err_unregister:
+ unregister_netdevice(dev);
+ return err;
-err_free_flow:
- tun_flow_uninit(tun);
- security_tun_dev_free_security(tun->security);
err_free_stat:
free_percpu(tun->pcpu_stats);
err_free_dev:
@@ -2979,6 +2981,8 @@ static int tun_set_queue(struct file *file, struct ifreq *ifr)
goto unlock;
ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI,
tun->flags & IFF_NAPI_FRAGS);
+ if (!ret)
+ tun_set_real_num_queues(tun, tun->numqueues);
} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
tun = rtnl_dereference(tfile->tun);
if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)
--
2.17.1
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