From: Matthew Rosato <mjrosato@linux•vnet.ibm.com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: davem@davemloft•net, netdev@vger•kernel.org
Subject: Re: [PATCH] net_sched: check skb_transport_header_was_set() in qdisc_pkt_len_init()
Date: Mon, 20 May 2013 16:32:16 -0400 [thread overview]
Message-ID: <519A8850.8010209@linux.vnet.ibm.com> (raw)
In-Reply-To: <1369076323.3301.200.camel@edumazet-glaptop>
On 05/20/2013 02:58 PM, Eric Dumazet wrote:
> On Mon, 2013-05-20 at 14:47 -0400, Matthew Rosato wrote:
>> commit 1def9238d4aa2 (net_sched: more precise pkt_len computation) does
>> not check to see if skb_transport_header is valid prior to using it in
>> qdisc_pkt_len_init(), which can lead to a kernel panic if
>> skb_transport_header is not valid but gso_size is nonzero. This patch
>> adds a check for skb_transport_header_was_set().
>>
>> I managed to hit this scenario by driving a burst of traffic from a
>> qemu guest through a macvtap interface, causing a panic in the host kernel.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@linux•vnet.ibm.com>
>> ---
>> net/core/dev.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index fc1e289..5d0d3af 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -2596,7 +2596,7 @@ static void qdisc_pkt_len_init(struct sk_buff *skb)
>> /* To get more precise estimation of bytes sent on wire,
>> * we add to pkt_len the headers size of all segments
>> */
>> - if (shinfo->gso_size) {
>> + if (shinfo->gso_size && skb_transport_header_was_set(skb)) {
>> unsigned int hdr_len;
>> u16 gso_segs = shinfo->gso_segs;
>>
>
> Have you tried a recent kernel ?
>
> I believe this was already discussed.
Mea Culpa. You are correct, I was missing a macvtap fix that already
resolves this issue. For the sake of documentation, that fix is
9b4d669bc06c2 macvtap: set transport header before passing skb to lower
device.
Applied and verified that problem is resolved. You can consider this
patch withdrawn. Thanks.
>
> Please fix macvtap instead if its still buggy.
>
>
next prev parent reply other threads:[~2013-05-20 20:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-20 18:47 [PATCH] net_sched: check skb_transport_header_was_set() in qdisc_pkt_len_init() Matthew Rosato
2013-05-20 18:58 ` Eric Dumazet
2013-05-20 20:32 ` Matthew Rosato [this message]
2013-05-20 20:37 ` Eric Dumazet
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