From: Mark Lord <mlord@pobox•com>
To: Eric Dumazet <eric.dumazet@gmail•com>,
Ming Lei <ming.lei@canonical•com>,
davem@davemloft•net, netdev@vger•kernel.org
Subject: Re: net/usb/ax88179_178a driver broken in linux-3.12
Date: Sun, 17 Nov 2013 14:04:33 -0500 [thread overview]
Message-ID: <52891341.4020403@pobox.com> (raw)
In-Reply-To: <52891178.2080509@pobox.com>
On 13-11-17 01:56 PM, Mark Lord wrote:
> On 13-11-17 01:35 PM, Mark Lord wrote:
>> The USB3 network adapter locks up consistently for me here in 3.12,
>> but was working without issues in 3.11.x
>>
>> Source of the problem is this patch:
>> http://patchwork.ozlabs.org/patch/264021/
>>
>> Reverting the patch fixes the adapter.
>
> Okay, upon closer inspection, the bug appears to be a math error.
> Here's a simpler (non-revert) patch to fix the bug that was introduced in 3.12.
>
> (un-mangled copy attached; reproduced below for ease of viewing).
>
> Don't exceed more than the 8 bytes of reserved ("needed_headroom") space
> when calling pskb_expand_head. This fixes a bug introduced in linux-3.12.0.
>
> Signed-off-by: Mark Lord <mlord@pobox•com>
>
>
> --- ax88179_178a.c.orig 2013-11-03 18:41:51.000000000 -0500
> +++ linux/drivers/net/usb/ax88179_178a.c 2013-11-17 13:47:26.127971404 -0500
> @@ -1183,10 +1183,10 @@
> if (((skb->len + 8) % frame_size) == 0)
> tx_hdr2 |= 0x80008000; /* Enable padding */
>
> - headroom = skb_headroom(skb) - 8;
> + headroom = skb_headroom(skb);
>
> - if ((skb_header_cloned(skb) || headroom < 0) &&
> - pskb_expand_head(skb, headroom < 0 ? 8 : 0, 0, GFP_ATOMIC)) {
> + if ((skb_header_cloned(skb) || headroom < 8) &&
> + pskb_expand_head(skb, headroom < 8 ? 8 - headroom : 0, 0, GFP_ATOMIC)) {
> dev_kfree_skb_any(skb);
> return NULL;
> }
>
Dagnabbit.. that still locked up just after I sent the email,
despite working fine in testing prior to that.
So.. sticking with the full revert here for now.
Perhaps one of you chaps can spot the bug.
--
Mark Lord
Real-Time Remedies Inc.
mlord@pobox•com
next prev parent reply other threads:[~2013-11-17 19:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <52890C7E.6000607@pobox.com>
2013-11-17 18:56 ` net/usb/ax88179_178a driver broken in linux-3.12 Mark Lord
2013-11-17 19:04 ` Mark Lord [this message]
2013-11-18 10:12 ` David Laight
2013-11-18 13:32 ` David Laight
2013-11-18 22:52 ` Mark Lord
2013-11-19 10:04 ` David Laight
2013-11-19 13:44 ` Mark Lord
2013-11-19 13:56 ` David Laight
2013-11-19 14:02 ` Mark Lord
2013-11-19 14:15 ` Eric Dumazet
2013-11-19 14:24 ` Mark Lord
2013-11-19 14:43 ` David Laight
2013-11-19 16:10 ` Eric Dumazet
2013-11-19 16:26 ` David Laight
2013-11-19 21:13 ` David Miller
2013-11-20 9:54 ` David Laight
2013-11-20 16:54 ` Sarah Sharp
2013-11-30 2:58 ` Mark Lord
[not found] ` <5299546B.2020800-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
2013-12-02 9:30 ` David Laight
2013-12-02 15:05 ` Mark Lord
[not found] ` <529CA1D2.2070806-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
2013-12-02 19:08 ` Sarah Sharp
2013-12-02 19:11 ` Mark Lord
2013-12-02 19:18 ` Greg KH
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