* [PATCH] net: fix skb use after free in netpoll_send_skb_on_dev
@ 2019-08-23 16:32 Feng Sun
2019-08-26 2:48 ` David Miller
2019-08-26 6:13 ` [PATCH v2] net: fix skb use after free in netpoll Feng Sun
0 siblings, 2 replies; 6+ messages in thread
From: Feng Sun @ 2019-08-23 16:32 UTC (permalink / raw)
To: davem
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, Feng Sun, Xiaojun Zhao
After commit baeababb5b85d5c4e6c917efe2a1504179438d3b
("tun: return NET_XMIT_DROP for dropped packets"),
when tun_net_xmit drop packets, it will free skb and return NET_XMIT_DROP,
netpoll_send_skb_on_dev will run into two use after free cases:
1. retry netpoll_start_xmit with freed skb;
2. queue freed skb in npinfo->txq.
hit the first case with following kernel log:
[ 117.864773] kernel BUG at mm/slub.c:306!
[ 117.864773] invalid opcode: 0000 [#1] SMP PTI
[ 117.864774] CPU: 3 PID: 2627 Comm: loop_printmsg Kdump: loaded Tainted: P OE 5.3.0-050300rc5-generic #201908182231
[ 117.864775] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 117.864775] RIP: 0010:kmem_cache_free+0x28d/0x2b0
[ 117.864781] Call Trace:
[ 117.864781] ? tun_net_xmit+0x21c/0x460
[ 117.864781] kfree_skbmem+0x4e/0x60
[ 117.864782] kfree_skb+0x3a/0xa0
[ 117.864782] tun_net_xmit+0x21c/0x460
[ 117.864782] netpoll_start_xmit+0x11d/0x1b0
[ 117.864788] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864789] __br_forward+0x1b9/0x1e0 [bridge]
[ 117.864789] ? skb_clone+0x53/0xd0
[ 117.864790] ? __skb_clone+0x2e/0x120
[ 117.864790] deliver_clone+0x37/0x50 [bridge]
[ 117.864790] maybe_deliver+0x89/0xc0 [bridge]
[ 117.864791] br_flood+0x6c/0x130 [bridge]
[ 117.864791] br_dev_xmit+0x315/0x3c0 [bridge]
[ 117.864792] netpoll_start_xmit+0x11d/0x1b0
[ 117.864792] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864792] netpoll_send_udp+0x2c6/0x3e8
[ 117.864793] write_msg+0xd9/0xf0 [netconsole]
[ 117.864793] console_unlock+0x386/0x4e0
[ 117.864793] vprintk_emit+0x17e/0x280
[ 117.864794] vprintk_default+0x29/0x50
[ 117.864794] vprintk_func+0x4c/0xbc
[ 117.864794] printk+0x58/0x6f
[ 117.864795] loop_fun+0x24/0x41 [printmsg_loop]
[ 117.864795] kthread+0x104/0x140
[ 117.864795] ? 0xffffffffc05b1000
[ 117.864796] ? kthread_park+0x80/0x80
[ 117.864796] ret_from_fork+0x35/0x40
Signed-off-by: Feng Sun <loyou85@gmail.com>
Signed-off-by: Xiaojun Zhao <xiaojunzhao141@gmail.com>
---
net/core/netpoll.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 2cf27da..b4bffe6 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -335,7 +335,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
HARD_TX_UNLOCK(dev, txq);
- if (status == NETDEV_TX_OK)
+ if (status == NETDEV_TX_OK || status == NET_XMIT_DROP)
break;
}
@@ -352,7 +352,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
}
- if (status != NETDEV_TX_OK) {
+ if (status != NETDEV_TX_OK && status != NET_XMIT_DROP) {
skb_queue_tail(&npinfo->txq, skb);
schedule_delayed_work(&npinfo->tx_work,0);
}
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] net: fix skb use after free in netpoll_send_skb_on_dev
2019-08-23 16:32 [PATCH] net: fix skb use after free in netpoll_send_skb_on_dev Feng Sun
@ 2019-08-26 2:48 ` David Miller
2019-08-26 6:13 ` [PATCH v2] net: fix skb use after free in netpoll Feng Sun
1 sibling, 0 replies; 6+ messages in thread
From: David Miller @ 2019-08-26 2:48 UTC (permalink / raw)
To: loyou85
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, xiaojunzhao141
From: Feng Sun <loyou85@gmail.com>
Date: Sat, 24 Aug 2019 00:32:00 +0800
> After commit baeababb5b85d5c4e6c917efe2a1504179438d3b
> ("tun: return NET_XMIT_DROP for dropped packets"),
> when tun_net_xmit drop packets, it will free skb and return NET_XMIT_DROP,
> netpoll_send_skb_on_dev will run into two use after free cases:
I don't know what to do here.
Really, the intention of the design is that the only valid
->ndo_start_xmit() values are those with macro names fitting the
pattern NETDEV_TX_*, which means only NETDEV_TX_OK and NETDEV_TX_BUSY
are valid.
NET_XMIT_* values are for qdisc ->enqueue() methods.
Note, particularly, that when ->ndo_start_xmit() values are propagated
through ->enqueue() calls they get masked out with NET_XMIT_MASK.
However, I see that most of the code doing enqueueing and invocation
of ->ndo_start_xmit() use the dev_xmit_complete() helper to check this
condition.
So probably that is what netpoll should be using as well.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] net: fix skb use after free in netpoll
2019-08-23 16:32 [PATCH] net: fix skb use after free in netpoll_send_skb_on_dev Feng Sun
2019-08-26 2:48 ` David Miller
@ 2019-08-26 6:13 ` Feng Sun
2019-08-26 6:20 ` David Miller
1 sibling, 1 reply; 6+ messages in thread
From: Feng Sun @ 2019-08-26 6:13 UTC (permalink / raw)
To: davem
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, Feng Sun, Xiaojun Zhao
After commit baeababb5b85d5c4e6c917efe2a1504179438d3b
("tun: return NET_XMIT_DROP for dropped packets"),
when tun_net_xmit drop packets, it will free skb and return NET_XMIT_DROP,
netpoll_send_skb_on_dev will run into following use after free cases:
1. retry netpoll_start_xmit with freed skb;
2. queue freed skb in npinfo->txq.
queue_process will also run into use after free case.
hit netpoll_send_skb_on_dev first case with following kernel log:
[ 117.864773] kernel BUG at mm/slub.c:306!
[ 117.864773] invalid opcode: 0000 [#1] SMP PTI
[ 117.864774] CPU: 3 PID: 2627 Comm: loop_printmsg Kdump: loaded Tainted: P OE 5.3.0-050300rc5-generic #201908182231
[ 117.864775] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 117.864775] RIP: 0010:kmem_cache_free+0x28d/0x2b0
[ 117.864781] Call Trace:
[ 117.864781] ? tun_net_xmit+0x21c/0x460
[ 117.864781] kfree_skbmem+0x4e/0x60
[ 117.864782] kfree_skb+0x3a/0xa0
[ 117.864782] tun_net_xmit+0x21c/0x460
[ 117.864782] netpoll_start_xmit+0x11d/0x1b0
[ 117.864788] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864789] __br_forward+0x1b9/0x1e0 [bridge]
[ 117.864789] ? skb_clone+0x53/0xd0
[ 117.864790] ? __skb_clone+0x2e/0x120
[ 117.864790] deliver_clone+0x37/0x50 [bridge]
[ 117.864790] maybe_deliver+0x89/0xc0 [bridge]
[ 117.864791] br_flood+0x6c/0x130 [bridge]
[ 117.864791] br_dev_xmit+0x315/0x3c0 [bridge]
[ 117.864792] netpoll_start_xmit+0x11d/0x1b0
[ 117.864792] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864792] netpoll_send_udp+0x2c6/0x3e8
[ 117.864793] write_msg+0xd9/0xf0 [netconsole]
[ 117.864793] console_unlock+0x386/0x4e0
[ 117.864793] vprintk_emit+0x17e/0x280
[ 117.864794] vprintk_default+0x29/0x50
[ 117.864794] vprintk_func+0x4c/0xbc
[ 117.864794] printk+0x58/0x6f
[ 117.864795] loop_fun+0x24/0x41 [printmsg_loop]
[ 117.864795] kthread+0x104/0x140
[ 117.864795] ? 0xffffffffc05b1000
[ 117.864796] ? kthread_park+0x80/0x80
[ 117.864796] ret_from_fork+0x35/0x40
Signed-off-by: Feng Sun <loyou85@gmail.com>
Signed-off-by: Xiaojun Zhao <xiaojunzhao141@gmail.com>
---
Changes in v2:
- change commit and title
- add netpoll_xmit_complete helper
- add one more return value check of netpoll_start_xmit
---
net/core/netpoll.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 2cf27da..a3f20e9 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -95,6 +95,11 @@ static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
return status;
}
+static inline bool netpoll_xmit_complete(int rc)
+{
+ return dev_xmit_complete(rc);
+}
+
static void queue_process(struct work_struct *work)
{
struct netpoll_info *npinfo =
@@ -122,7 +127,7 @@ static void queue_process(struct work_struct *work)
txq = netdev_get_tx_queue(dev, q_index);
HARD_TX_LOCK(dev, txq, smp_processor_id());
if (netif_xmit_frozen_or_stopped(txq) ||
- netpoll_start_xmit(skb, dev, txq) != NETDEV_TX_OK) {
+ !netpoll_xmit_complete(netpoll_start_xmit(skb, dev, txq))) {
skb_queue_head(&npinfo->txq, skb);
HARD_TX_UNLOCK(dev, txq);
local_irq_restore(flags);
@@ -335,7 +340,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
HARD_TX_UNLOCK(dev, txq);
- if (status == NETDEV_TX_OK)
+ if (netpoll_xmit_complete(status))
break;
}
@@ -352,7 +357,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
}
- if (status != NETDEV_TX_OK) {
+ if (!netpoll_xmit_complete(status)) {
skb_queue_tail(&npinfo->txq, skb);
schedule_delayed_work(&npinfo->tx_work,0);
}
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] net: fix skb use after free in netpoll
2019-08-26 6:13 ` [PATCH v2] net: fix skb use after free in netpoll Feng Sun
@ 2019-08-26 6:20 ` David Miller
2019-08-26 6:46 ` [PATCH v3] " Feng Sun
0 siblings, 1 reply; 6+ messages in thread
From: David Miller @ 2019-08-26 6:20 UTC (permalink / raw)
To: loyou85
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, xiaojunzhao141
From: Feng Sun <loyou85@gmail.com>
Date: Mon, 26 Aug 2019 14:13:40 +0800
> +static inline bool netpoll_xmit_complete(int rc)
> +{
> + return dev_xmit_complete(rc);
> +}
There is no need for this useless indirection, just call dev_xmit_complete()
staright.
Also, even if it was suitable, never use the inline keyword in foo.c files.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v3] net: fix skb use after free in netpoll
2019-08-26 6:20 ` David Miller
@ 2019-08-26 6:46 ` Feng Sun
2019-08-28 3:52 ` David Miller
0 siblings, 1 reply; 6+ messages in thread
From: Feng Sun @ 2019-08-26 6:46 UTC (permalink / raw)
To: davem
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, Feng Sun, Xiaojun Zhao
After commit baeababb5b85d5c4e6c917efe2a1504179438d3b
("tun: return NET_XMIT_DROP for dropped packets"),
when tun_net_xmit drop packets, it will free skb and return NET_XMIT_DROP,
netpoll_send_skb_on_dev will run into following use after free cases:
1. retry netpoll_start_xmit with freed skb;
2. queue freed skb in npinfo->txq.
queue_process will also run into use after free case.
hit netpoll_send_skb_on_dev first case with following kernel log:
[ 117.864773] kernel BUG at mm/slub.c:306!
[ 117.864773] invalid opcode: 0000 [#1] SMP PTI
[ 117.864774] CPU: 3 PID: 2627 Comm: loop_printmsg Kdump: loaded Tainted: P OE 5.3.0-050300rc5-generic #201908182231
[ 117.864775] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 117.864775] RIP: 0010:kmem_cache_free+0x28d/0x2b0
[ 117.864781] Call Trace:
[ 117.864781] ? tun_net_xmit+0x21c/0x460
[ 117.864781] kfree_skbmem+0x4e/0x60
[ 117.864782] kfree_skb+0x3a/0xa0
[ 117.864782] tun_net_xmit+0x21c/0x460
[ 117.864782] netpoll_start_xmit+0x11d/0x1b0
[ 117.864788] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864789] __br_forward+0x1b9/0x1e0 [bridge]
[ 117.864789] ? skb_clone+0x53/0xd0
[ 117.864790] ? __skb_clone+0x2e/0x120
[ 117.864790] deliver_clone+0x37/0x50 [bridge]
[ 117.864790] maybe_deliver+0x89/0xc0 [bridge]
[ 117.864791] br_flood+0x6c/0x130 [bridge]
[ 117.864791] br_dev_xmit+0x315/0x3c0 [bridge]
[ 117.864792] netpoll_start_xmit+0x11d/0x1b0
[ 117.864792] netpoll_send_skb_on_dev+0x1b8/0x200
[ 117.864792] netpoll_send_udp+0x2c6/0x3e8
[ 117.864793] write_msg+0xd9/0xf0 [netconsole]
[ 117.864793] console_unlock+0x386/0x4e0
[ 117.864793] vprintk_emit+0x17e/0x280
[ 117.864794] vprintk_default+0x29/0x50
[ 117.864794] vprintk_func+0x4c/0xbc
[ 117.864794] printk+0x58/0x6f
[ 117.864795] loop_fun+0x24/0x41 [printmsg_loop]
[ 117.864795] kthread+0x104/0x140
[ 117.864795] ? 0xffffffffc05b1000
[ 117.864796] ? kthread_park+0x80/0x80
[ 117.864796] ret_from_fork+0x35/0x40
Signed-off-by: Feng Sun <loyou85@gmail.com>
Signed-off-by: Xiaojun Zhao <xiaojunzhao141@gmail.com>
---
Changes in v3:
- use dev_xmit_complete directly
Changes in v2:
- change commit and title
- add netpoll_xmit_complete helper
- add one more return value check of netpoll_start_xmit
---
net/core/netpoll.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 2cf27da..849380a6 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -122,7 +122,7 @@ static void queue_process(struct work_struct *work)
txq = netdev_get_tx_queue(dev, q_index);
HARD_TX_LOCK(dev, txq, smp_processor_id());
if (netif_xmit_frozen_or_stopped(txq) ||
- netpoll_start_xmit(skb, dev, txq) != NETDEV_TX_OK) {
+ !dev_xmit_complete(netpoll_start_xmit(skb, dev, txq))) {
skb_queue_head(&npinfo->txq, skb);
HARD_TX_UNLOCK(dev, txq);
local_irq_restore(flags);
@@ -335,7 +335,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
HARD_TX_UNLOCK(dev, txq);
- if (status == NETDEV_TX_OK)
+ if (dev_xmit_complete(status))
break;
}
@@ -352,7 +352,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
}
- if (status != NETDEV_TX_OK) {
+ if (!dev_xmit_complete(status)) {
skb_queue_tail(&npinfo->txq, skb);
schedule_delayed_work(&npinfo->tx_work,0);
}
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v3] net: fix skb use after free in netpoll
2019-08-26 6:46 ` [PATCH v3] " Feng Sun
@ 2019-08-28 3:52 ` David Miller
0 siblings, 0 replies; 6+ messages in thread
From: David Miller @ 2019-08-28 3:52 UTC (permalink / raw)
To: loyou85
Cc: edumazet, dsterba, dbanerje, fw, davej, tglx, matwey,
sakari.ailus, netdev, linux-kernel, xiaojunzhao141
From: Feng Sun <loyou85@gmail.com>
Date: Mon, 26 Aug 2019 14:46:04 +0800
> After commit baeababb5b85d5c4e6c917efe2a1504179438d3b
> ("tun: return NET_XMIT_DROP for dropped packets"),
> when tun_net_xmit drop packets, it will free skb and return NET_XMIT_DROP,
> netpoll_send_skb_on_dev will run into following use after free cases:
> 1. retry netpoll_start_xmit with freed skb;
> 2. queue freed skb in npinfo->txq.
> queue_process will also run into use after free case.
>
> hit netpoll_send_skb_on_dev first case with following kernel log:
...
> Signed-off-by: Feng Sun <loyou85@gmail.com>
> Signed-off-by: Xiaojun Zhao <xiaojunzhao141@gmail.com>
Applied and queued up for -stable.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-08-28 3:52 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-23 16:32 [PATCH] net: fix skb use after free in netpoll_send_skb_on_dev Feng Sun
2019-08-26 2:48 ` David Miller
2019-08-26 6:13 ` [PATCH v2] net: fix skb use after free in netpoll Feng Sun
2019-08-26 6:20 ` David Miller
2019-08-26 6:46 ` [PATCH v3] " Feng Sun
2019-08-28 3:52 ` David Miller
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