[PATCH net 0/3] Several fixes for vhost_net ptr_ring usage

[PATCH net 0/3] Several fixes for vhost_net ptr_ring usage

[Jason Wang]

Hi:

This small series try to fix several bugs of ptr_ring usage in
vhost_net. Please review.

Thanks

Alexander Potapenko (1):
  vhost_net: initialize rx_ring in vhost_net_open()

Jason Wang (2):
  vhost_net: keep private_data and rx_ring synced
  vhost_net: examine pointer types during un-producing

 drivers/net/tun.c      | 3 ++-
 drivers/vhost/net.c    | 8 +++++---
 include/linux/if_tun.h | 4 ++++
 3 files changed, 11 insertions(+), 4 deletions(-)

-- 
2.7.4

[PATCH net 1/3] vhost_net: initialize rx_ring in vhost_net_open()

[Jason Wang]

From: Alexander Potapenko <glider@google.com>

KMSAN reported a use of uninit memory in vhost_net_buf_unproduce()
while trying to access n->vqs[VHOST_NET_VQ_TX].rx_ring:

==================================================================
BUG: KMSAN: use of uninitialized memory in vhost_net_buf_unproduce+0x7bb/0x9a0 drivers/vho
et.c:170
CPU: 0 PID: 3021 Comm: syz-fuzzer Not tainted 4.16.0-rc4+ #3853
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x1f0 mm/kmsan/kmsan.c:1093
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
 vhost_net_buf_unproduce+0x7bb/0x9a0 drivers/vhost/net.c:170
 vhost_net_stop_vq drivers/vhost/net.c:974 [inline]
 vhost_net_stop+0x146/0x380 drivers/vhost/net.c:982
 vhost_net_release+0xb1/0x4f0 drivers/vhost/net.c:1015
 __fput+0x49f/0xa00 fs/file_table.c:209
 ____fput+0x37/0x40 fs/file_table.c:243
 task_work_run+0x243/0x2c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:166 [inline]
 prepare_exit_to_usermode+0x349/0x3b0 arch/x86/entry/common.c:196
 syscall_return_slowpath+0xf3/0x6d0 arch/x86/entry/common.c:265
 do_syscall_64+0x34d/0x450 arch/x86/entry/common.c:292
...
origin:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:303 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:213
 kmsan_kmalloc_large+0x6f/0xd0 mm/kmsan/kmsan.c:392
 kmalloc_large_node_hook mm/slub.c:1366 [inline]
 kmalloc_large_node mm/slub.c:3808 [inline]
 __kmalloc_node+0x100e/0x1290 mm/slub.c:3818
 kmalloc_node include/linux/slab.h:554 [inline]
 kvmalloc_node+0x1a5/0x2e0 mm/util.c:419
 kvmalloc include/linux/mm.h:541 [inline]
 vhost_net_open+0x64/0x5f0 drivers/vhost/net.c:921
 misc_open+0x7b5/0x8b0 drivers/char/misc.c:154
 chrdev_open+0xc28/0xd90 fs/char_dev.c:417
 do_dentry_open+0xccb/0x1430 fs/open.c:752
 vfs_open+0x272/0x2e0 fs/open.c:866
 do_last fs/namei.c:3378 [inline]
 path_openat+0x49ad/0x6580 fs/namei.c:3519
 do_filp_open+0x267/0x640 fs/namei.c:3553
 do_sys_open+0x6ad/0x9c0 fs/open.c:1059
 SYSC_openat+0xc7/0xe0 fs/open.c:1086
 SyS_openat+0x63/0x90 fs/open.c:1080
 do_syscall_64+0x2f1/0x450 arch/x86/entry/common.c:287
==================================================================

Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/net.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 610cba2..60f1080 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -948,6 +948,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
 		n->vqs[i].done_idx = 0;
 		n->vqs[i].vhost_hlen = 0;
 		n->vqs[i].sock_hlen = 0;
+		n->vqs[i].rx_ring = NULL;
 		vhost_net_buf_init(&n->vqs[i].rxq);
 	}
 	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
-- 
2.7.4

[PATCH net 2/3] vhost_net: keep private_data and rx_ring synced

[Jason Wang]

We get pointer ring from the exported sock, this means we should keep
rx_ring and vq->private synced during both vq stop and backend set,
otherwise we may see stale rx_ring.

Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/net.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 60f1080..efb9306 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -973,6 +973,7 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 	vhost_net_disable_vq(n, vq);
 	vq->private_data = NULL;
 	vhost_net_buf_unproduce(nvq);
+	nvq->rx_ring = NULL;
 	mutex_unlock(&vq->mutex);
 	return sock;
 }
@@ -1162,14 +1163,14 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 		vhost_net_disable_vq(n, vq);
 		vq->private_data = sock;
 		vhost_net_buf_unproduce(nvq);
-		if (index == VHOST_NET_VQ_RX)
-			nvq->rx_ring = get_tap_ptr_ring(fd);
 		r = vhost_vq_init_access(vq);
 		if (r)
 			goto err_used;
 		r = vhost_net_enable_vq(n, vq);
 		if (r)
 			goto err_used;
+		if (index == VHOST_NET_VQ_RX)
+			nvq->rx_ring = get_tap_ptr_ring(fd);
 
 		oldubufs = nvq->ubufs;
 		nvq->ubufs = ubufs;
-- 
2.7.4

[PATCH net 3/3] vhost_net: examine pointer types during un-producing

[Jason Wang]

After commit fc72d1d54dd9 ("tuntap: XDP transmission"), we can
actually queueing XDP pointers in the pointer ring, so we should
examine the pointer type before freeing the pointer.

Fixes: fc72d1d54dd9 ("tuntap: XDP transmission")
Reported-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c      | 3 ++-
 drivers/vhost/net.c    | 2 +-
 include/linux/if_tun.h | 4 ++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7433bb2..28cfa64 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -655,7 +655,7 @@ static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
 	return tun;
 }
 
-static void tun_ptr_free(void *ptr)
+void tun_ptr_free(void *ptr)
 {
 	if (!ptr)
 		return;
@@ -667,6 +667,7 @@ static void tun_ptr_free(void *ptr)
 		__skb_array_destroy_skb(ptr);
 	}
 }
+EXPORT_SYMBOL_GPL(tun_ptr_free);
 
 static void tun_queue_purge(struct tun_file *tfile)
 {
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index efb9306..8139bc7 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -170,7 +170,7 @@ static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
 	if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
 		ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
 				   vhost_net_buf_get_size(rxq),
-				   __skb_array_destroy_skb);
+				   tun_ptr_free);
 		rxq->head = rxq->tail = 0;
 	}
 }
diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index c5b0a75..fd00170 100644
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -25,6 +25,7 @@ struct ptr_ring *tun_get_tx_ring(struct file *file);
 bool tun_is_xdp_buff(void *ptr);
 void *tun_xdp_to_ptr(void *ptr);
 void *tun_ptr_to_xdp(void *ptr);
+void tun_ptr_free(void *ptr);
 #else
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -50,5 +51,8 @@ static inline void *tun_ptr_to_xdp(void *ptr)
 {
 	return NULL;
 }
+static inline void tun_ptr_free(void *ptr)
+{
+}
 #endif /* CONFIG_TUN */
 #endif /* __IF_TUN_H */
-- 
2.7.4

Re: [PATCH net 1/3] vhost_net: initialize rx_ring in vhost_net_open()

[Michael S. Tsirkin]

On Fri, Mar 09, 2018 at 02:50:32PM +0800, Jason Wang wrote:
> From: Alexander Potapenko <glider@google.com>
> 
> KMSAN reported a use of uninit memory in vhost_net_buf_unproduce()
> while trying to access n->vqs[VHOST_NET_VQ_TX].rx_ring:
> 
> ==================================================================
> BUG: KMSAN: use of uninitialized memory in vhost_net_buf_unproduce+0x7bb/0x9a0 drivers/vho
> et.c:170
> CPU: 0 PID: 3021 Comm: syz-fuzzer Not tainted 4.16.0-rc4+ #3853
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x185/0x1d0 lib/dump_stack.c:53
>  kmsan_report+0x142/0x1f0 mm/kmsan/kmsan.c:1093
>  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
>  vhost_net_buf_unproduce+0x7bb/0x9a0 drivers/vhost/net.c:170
>  vhost_net_stop_vq drivers/vhost/net.c:974 [inline]
>  vhost_net_stop+0x146/0x380 drivers/vhost/net.c:982
>  vhost_net_release+0xb1/0x4f0 drivers/vhost/net.c:1015
>  __fput+0x49f/0xa00 fs/file_table.c:209
>  ____fput+0x37/0x40 fs/file_table.c:243
>  task_work_run+0x243/0x2c0 kernel/task_work.c:113
>  tracehook_notify_resume include/linux/tracehook.h:191 [inline]
>  exit_to_usermode_loop arch/x86/entry/common.c:166 [inline]
>  prepare_exit_to_usermode+0x349/0x3b0 arch/x86/entry/common.c:196
>  syscall_return_slowpath+0xf3/0x6d0 arch/x86/entry/common.c:265
>  do_syscall_64+0x34d/0x450 arch/x86/entry/common.c:292
> ...
> origin:
>  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:303 [inline]
>  kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:213
>  kmsan_kmalloc_large+0x6f/0xd0 mm/kmsan/kmsan.c:392
>  kmalloc_large_node_hook mm/slub.c:1366 [inline]
>  kmalloc_large_node mm/slub.c:3808 [inline]
>  __kmalloc_node+0x100e/0x1290 mm/slub.c:3818
>  kmalloc_node include/linux/slab.h:554 [inline]
>  kvmalloc_node+0x1a5/0x2e0 mm/util.c:419
>  kvmalloc include/linux/mm.h:541 [inline]
>  vhost_net_open+0x64/0x5f0 drivers/vhost/net.c:921
>  misc_open+0x7b5/0x8b0 drivers/char/misc.c:154
>  chrdev_open+0xc28/0xd90 fs/char_dev.c:417
>  do_dentry_open+0xccb/0x1430 fs/open.c:752
>  vfs_open+0x272/0x2e0 fs/open.c:866
>  do_last fs/namei.c:3378 [inline]
>  path_openat+0x49ad/0x6580 fs/namei.c:3519
>  do_filp_open+0x267/0x640 fs/namei.c:3553
>  do_sys_open+0x6ad/0x9c0 fs/open.c:1059
>  SYSC_openat+0xc7/0xe0 fs/open.c:1086
>  SyS_openat+0x63/0x90 fs/open.c:1080
>  do_syscall_64+0x2f1/0x450 arch/x86/entry/common.c:287
> ==================================================================
> 
> Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
> Signed-off-by: Alexander Potapenko <glider@google.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/vhost/net.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 610cba2..60f1080 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -948,6 +948,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
>  		n->vqs[i].done_idx = 0;
>  		n->vqs[i].vhost_hlen = 0;
>  		n->vqs[i].sock_hlen = 0;
> +		n->vqs[i].rx_ring = NULL;
>  		vhost_net_buf_init(&n->vqs[i].rxq);
>  	}
>  	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
> -- 
> 2.7.4

Re: [PATCH net 2/3] vhost_net: keep private_data and rx_ring synced

[Michael S. Tsirkin]

On Fri, Mar 09, 2018 at 02:50:33PM +0800, Jason Wang wrote:
> We get pointer ring from the exported sock, this means we should keep
> rx_ring and vq->private synced during both vq stop and backend set,
> otherwise we may see stale rx_ring.
> 
> Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/vhost/net.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 60f1080..efb9306 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -973,6 +973,7 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
>  	vhost_net_disable_vq(n, vq);
>  	vq->private_data = NULL;
>  	vhost_net_buf_unproduce(nvq);
> +	nvq->rx_ring = NULL;
>  	mutex_unlock(&vq->mutex);
>  	return sock;
>  }
> @@ -1162,14 +1163,14 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>  		vhost_net_disable_vq(n, vq);
>  		vq->private_data = sock;
>  		vhost_net_buf_unproduce(nvq);
> -		if (index == VHOST_NET_VQ_RX)
> -			nvq->rx_ring = get_tap_ptr_ring(fd);
>  		r = vhost_vq_init_access(vq);
>  		if (r)
>  			goto err_used;
>  		r = vhost_net_enable_vq(n, vq);
>  		if (r)
>  			goto err_used;
> +		if (index == VHOST_NET_VQ_RX)
> +			nvq->rx_ring = get_tap_ptr_ring(fd);
>  
>  		oldubufs = nvq->ubufs;
>  		nvq->ubufs = ubufs;
> -- 
> 2.7.4

Re: [PATCH net 0/3] Several fixes for vhost_net ptr_ring usage

[Michael S. Tsirkin]

On Fri, Mar 09, 2018 at 02:50:31PM +0800, Jason Wang wrote:
> Hi:
> 
> This small series try to fix several bugs of ptr_ring usage in
> vhost_net. Please review.
> 
> Thanks

ACK series, thanks Jason!

> Alexander Potapenko (1):
>   vhost_net: initialize rx_ring in vhost_net_open()
> 
> Jason Wang (2):
>   vhost_net: keep private_data and rx_ring synced
>   vhost_net: examine pointer types during un-producing
> 
>  drivers/net/tun.c      | 3 ++-
>  drivers/vhost/net.c    | 8 +++++---
>  include/linux/if_tun.h | 4 ++++
>  3 files changed, 11 insertions(+), 4 deletions(-)
> 
> -- 
> 2.7.4

Re: [PATCH net 0/3] Several fixes for vhost_net ptr_ring usage

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Fri,  9 Mar 2018 14:50:31 +0800

> This small series try to fix several bugs of ptr_ring usage in
> vhost_net. Please review.

Series applied, thanks Jason.