Re: kernel panic with time-stamping in phy devices (monitor mode)

[Eric Dumazet <eric.dumazet@gmail.com>]

Le jeudi 02 décembre 2010 à 08:05 -0800, Andrew Watts a écrit :
> Hi.
> 
> The 'time stamping in phy devices' code introduced in 2.6.36
> (c1f19b51d1d87f3e3bb7e6648f43f7d57ed2da6b et al.) triggers
> kernel panics when wireless devices are placed in monitor mode
> (tested with b43 and ath5k devices on a 32-bit system).
> 
> To reproduce, set CONFIG_NETWORK_PHY_TIMESTAMPING=y and put a
> wireless device into monitor mode:
> 
>  # ifconfig wlan0 down
>  # iwconfig wlan0 mode monitor 
>  # ifconfig wlan0 up
> 
> ~ Andy
> 
> ==============
> 
>  [<c14455ad>] ? __alloc_skb+0x53/0xf8
>  [<f92fdd57>] ? b43_dma_rx+0x18a/0x342 [b43]
>  [<f92e8475>] ? b43_do_interrupt_thread+0x420/0x92e [b43]
>  [<c1027731>] ? __dequeue_entity+0x31/0x35
>  [<c1027a44>] ? set_next_entity+0xad/0xbb
>  [<f92e899b>] ? b43_interrupt_thread_handler+0x18/0x2b [b43]
>  [<c107c378>] ? irq_thread+0xb6/0x19e
>  [<c15625a0>] ? schedule+0x254/0x566
>  [<c107c2c2>] ? irq_thread+0x0/0x19e
>  [<c10448b1>] ? kthread+0x67/0x69
>  [<c104484a>] ? kthread+0x0/0x69
>  [<c100323e>] ? kernel_thread_helper+0x6/0x18
> Code: 4c 24 14 8b 88 a8 00 00 00 89 4c 24 10 89 54 24 0c 8b
> 40 50 89 44 24 08 8b 45 04 89 44 24 04 c7 04 24 30 74 7a c1
> e8 b5 d2 11 00 <0f> 0b eb fe 55 89 e5 56 53 83 ec 24 8b 88
> a0 00 00 00 8b 58 54
> EIP: [<c1444ea0>] skb_push+0x7d/0x81 SS:ESP 0068:cee01d78
> ---[ end trace af1c99818e62b195 ]---
> Kernel panic - not syncing: Fatal exception in interrupt
> Pid: 6674, comm: irq/18-b43 Tainted: G     D     2.6.36.1
> Call Trace:
>  [<c156217d>] ? printk+0x28/0x2a
>  [<c156205c>] panic+0x57/0x150
>  [<c1564adf>] oops_begin+0x0/0x40
>  [<c1004e36>] die+0x49/0x5d
>  [<c1564304>] do_trap+0x84/0xad
>  [<c10037e5>] ? do_invalid_op+0x0/0x93
>  [<c100386b>] do_invalid_op+0x86/0x93
>  [<c1444ea0>] ? skb_push+0x7d/0x81
>  [<c15640b9>] error_code+0x65/0x6c
>  [<c1444ea0>] ? skb_push+0x7d/0x81
>  [<c145f721>] ? skb_defer_rx_timestamp+0x12/0x5a
>  [<c145f721>] skb_defer_rx_timestamp+0x12/0x5a
>  [<c144d23c>] netif_receive_skb+0x1f/0x47
>  [<c153a6e8>] ieee80211_rx+0x661/0x8e1
>  [<f85daca2>] ? ssb_pci_read32+0x19/0x31 [ssb]
>  [<f92e54cf>] ? b43_tsf_read+0x2a/0x47 [b43]
>  [<f92f8d42>] b43_rx+0x24c/0x5eb [b43]
>  [<c14455ad>] ? __alloc_skb+0x53/0xf8
>  [<f92fdd57>] b43_dma_rx+0x18a/0x342 [b43]
>  [<f92e8475>] b43_do_interrupt_thread+0x420/0x92e [b43]
>  [<c1027731>] ? __dequeue_entity+0x31/0x35
>  [<c1027a44>] ? set_next_entity+0xad/0xbb
>  [<f92e899b>] b43_interrupt_thread_handler+0x18/0x2b [b43]
>  [<c107c378>] irq_thread+0xb6/0x19e
>  [<c15625a0>] ? schedule+0x254/0x566
>  [<c107c2c2>] ? irq_thread+0x0/0x19e
>  [<c10448b1>] kthread+0x67/0x69
>  [<c104484a>] ? kthread+0x0/0x69
>  [<c100323e>] kernel_thread_helper+0x6/0x18
> 
> 

Thanks for the report

Please try following patch.

diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index dac7ed6..a710ab0 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -96,7 +96,10 @@ bool skb_defer_rx_timestamp(struct sk_buff *skb)
 	struct phy_device *phydev;
 	unsigned int type;
 
-	skb_push(skb, ETH_HLEN);
+	if (skb->data - ETH_HLEN < skb->head)
+		return false;
+
+	__skb_push(skb, ETH_HLEN);
 
 	type = classify(skb);