[v4] tun: fix use-after-free when register netdev failed
diff mbox series

Message ID 1568113017-79840-1-git-send-email-yangyingliang@huawei.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • [v4] tun: fix use-after-free when register netdev failed
Related show

Commit Message

Yang Yingliang Sept. 10, 2019, 10:56 a.m. UTC
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()
                                                    tun_do_read()
                                                      tun_ring_recv()
    register_netdevice() <-- inject error
    goto err_detach
    tun_detach_all() <-- set RCV_SHUTDOWN
    free_netdev() <-- called from
                     err_free_dev path
      netdev_freemem() <-- free the memory
                        without check refcount
      (In this path, the refcount cannot prevent
       freeing the memory of dev, and the memory
       will be used by dev_put() called by
       tun_chr_read_iter() on CPUB.)
                                                     (Break from tun_ring_recv(),
                                                     because RCV_SHUTDOWN is set)
                                                   tun_put()
                                                     dev_put() <-- use the memory
                                                                   freed by netdev_freemem()

Put the publishing of tfile->tun after register_netdevice(),
so tun_get() won't get the tun pointer that freed by
err_detach path if register_netdevice() failed.

Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice")
Reported-by: Hulk Robot <hulkci@huawei.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/net/tun.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

Comments

Jason Wang Sept. 11, 2019, 2:57 a.m. UTC | #1
On 2019/9/10 下午6:56, Yang Yingliang wrote:
> 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()
>                                                      tun_do_read()
>                                                        tun_ring_recv()
>      register_netdevice() <-- inject error
>      goto err_detach
>      tun_detach_all() <-- set RCV_SHUTDOWN
>      free_netdev() <-- called from
>                       err_free_dev path
>        netdev_freemem() <-- free the memory
>                          without check refcount
>        (In this path, the refcount cannot prevent
>         freeing the memory of dev, and the memory
>         will be used by dev_put() called by
>         tun_chr_read_iter() on CPUB.)
>                                                       (Break from tun_ring_recv(),
>                                                       because RCV_SHUTDOWN is set)
>                                                     tun_put()
>                                                       dev_put() <-- use the memory
>                                                                     freed by netdev_freemem()
>
> Put the publishing of tfile->tun after register_netdevice(),
> so tun_get() won't get the tun pointer that freed by
> err_detach path if register_netdevice() failed.
>
> Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Suggested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
>   drivers/net/tun.c | 16 +++++++++++-----
>   1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index db16d7a13e00..aab0be40d443 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -787,7 +787,8 @@ static void tun_detach_all(struct net_device *dev)
>   }
>   
>   static int tun_attach(struct tun_struct *tun, struct file *file,
> -		      bool skip_filter, bool napi, bool napi_frags)
> +		      bool skip_filter, bool napi, bool napi_frags,
> +		      bool publish_tun)
>   {
>   	struct tun_file *tfile = file->private_data;
>   	struct net_device *dev = tun->dev;
> @@ -870,7 +871,8 @@ static int tun_attach(struct tun_struct *tun, struct file *file,
>   	 * initialized tfile; otherwise we risk using half-initialized
>   	 * object.
>   	 */
> -	rcu_assign_pointer(tfile->tun, tun);
> +	if (publish_tun)
> +		rcu_assign_pointer(tfile->tun, tun);
>   	rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
>   	tun->numqueues++;
>   	tun_set_real_num_queues(tun);
> @@ -2730,7 +2732,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>   
>   		err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER,
>   				 ifr->ifr_flags & IFF_NAPI,
> -				 ifr->ifr_flags & IFF_NAPI_FRAGS);
> +				 ifr->ifr_flags & IFF_NAPI_FRAGS, true);
>   		if (err < 0)
>   			return err;
>   
> @@ -2829,13 +2831,17 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>   
>   		INIT_LIST_HEAD(&tun->disabled);
>   		err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI,
> -				 ifr->ifr_flags & IFF_NAPI_FRAGS);
> +				 ifr->ifr_flags & IFF_NAPI_FRAGS, false);
>   		if (err < 0)
>   			goto err_free_flow;
>   
>   		err = register_netdevice(tun->dev);
>   		if (err < 0)
>   			goto err_detach;
> +		/* free_netdev() won't check refcnt, to aovid race


A typo that comes from my original patch "avoid".

Other  looks good.

Thanks


> +		 * with dev_put() we need publish tun after registration.
> +		 */
> +		rcu_assign_pointer(tfile->tun, tun);
>   	}
>   
>   	netif_carrier_on(tun->dev);
> @@ -2978,7 +2984,7 @@ static int tun_set_queue(struct file *file, struct ifreq *ifr)
>   		if (ret < 0)
>   			goto unlock;
>   		ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI,
> -				 tun->flags & IFF_NAPI_FRAGS);
> +				 tun->flags & IFF_NAPI_FRAGS, true);
>   	} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
>   		tun = rtnl_dereference(tfile->tun);
>   		if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)
David Miller Sept. 12, 2019, 10:18 a.m. UTC | #2
From: Yang Yingliang <yangyingliang@huawei.com>
Date: Tue, 10 Sep 2019 18:56:57 +0800

> I got a UAF repport in tun driver when doing fuzzy test:
 ...
> 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()
>                                                     tun_do_read()
>                                                       tun_ring_recv()
>     register_netdevice() <-- inject error
>     goto err_detach
>     tun_detach_all() <-- set RCV_SHUTDOWN
>     free_netdev() <-- called from
>                      err_free_dev path
>       netdev_freemem() <-- free the memory
>                         without check refcount
>       (In this path, the refcount cannot prevent
>        freeing the memory of dev, and the memory
>        will be used by dev_put() called by
>        tun_chr_read_iter() on CPUB.)
>                                                      (Break from tun_ring_recv(),
>                                                      because RCV_SHUTDOWN is set)
>                                                    tun_put()
>                                                      dev_put() <-- use the memory
>                                                                    freed by netdev_freemem()
> 
> Put the publishing of tfile->tun after register_netdevice(),
> so tun_get() won't get the tun pointer that freed by
> err_detach path if register_netdevice() failed.
> 
> Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Suggested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

Applied, thanks.

Patch
diff mbox series

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index db16d7a13e00..aab0be40d443 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -787,7 +787,8 @@  static void tun_detach_all(struct net_device *dev)
 }
 
 static int tun_attach(struct tun_struct *tun, struct file *file,
-		      bool skip_filter, bool napi, bool napi_frags)
+		      bool skip_filter, bool napi, bool napi_frags,
+		      bool publish_tun)
 {
 	struct tun_file *tfile = file->private_data;
 	struct net_device *dev = tun->dev;
@@ -870,7 +871,8 @@  static int tun_attach(struct tun_struct *tun, struct file *file,
 	 * initialized tfile; otherwise we risk using half-initialized
 	 * object.
 	 */
-	rcu_assign_pointer(tfile->tun, tun);
+	if (publish_tun)
+		rcu_assign_pointer(tfile->tun, tun);
 	rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
 	tun->numqueues++;
 	tun_set_real_num_queues(tun);
@@ -2730,7 +2732,7 @@  static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 
 		err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER,
 				 ifr->ifr_flags & IFF_NAPI,
-				 ifr->ifr_flags & IFF_NAPI_FRAGS);
+				 ifr->ifr_flags & IFF_NAPI_FRAGS, true);
 		if (err < 0)
 			return err;
 
@@ -2829,13 +2831,17 @@  static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 
 		INIT_LIST_HEAD(&tun->disabled);
 		err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI,
-				 ifr->ifr_flags & IFF_NAPI_FRAGS);
+				 ifr->ifr_flags & IFF_NAPI_FRAGS, false);
 		if (err < 0)
 			goto err_free_flow;
 
 		err = register_netdevice(tun->dev);
 		if (err < 0)
 			goto err_detach;
+		/* free_netdev() won't check refcnt, to aovid race
+		 * with dev_put() we need publish tun after registration.
+		 */
+		rcu_assign_pointer(tfile->tun, tun);
 	}
 
 	netif_carrier_on(tun->dev);
@@ -2978,7 +2984,7 @@  static int tun_set_queue(struct file *file, struct ifreq *ifr)
 		if (ret < 0)
 			goto unlock;
 		ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI,
-				 tun->flags & IFF_NAPI_FRAGS);
+				 tun->flags & IFF_NAPI_FRAGS, true);
 	} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
 		tun = rtnl_dereference(tfile->tun);
 		if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)