Xuan Zhuo
2021-Jun-04 02:30 UTC
[PATCH net] virtio-net: fix for skb_over_panic inside big mode
On Fri, 4 Jun 2021 10:28:41 +0800, Jason Wang <jasowang at redhat.com> wrote:> > ? 2021/6/4 ??1:09, Xuan Zhuo ??: > > In virtio-net's large packet mode, there is a hole in the space behind > > buf. > > > before the buf actually or behind the vnet header? > > > > > > hdr_padded_len - hdr_len > > > > We must take this into account when calculating tailroom. > > > > [ 44.544385] skb_put.cold (net/core/skbuff.c:5254 (discriminator 1) net/core/skbuff.c:5252 (discriminator 1)) > > [ 44.544864] page_to_skb (drivers/net/virtio_net.c:485) [ 44.545361] receive_buf (drivers/net/virtio_net.c:849 drivers/net/virtio_net.c:1131) > > [ 44.545870] ? netif_receive_skb_list_internal (net/core/dev.c:5714) > > [ 44.546628] ? dev_gro_receive (net/core/dev.c:6103) > > [ 44.547135] ? napi_complete_done (./include/linux/list.h:35 net/core/dev.c:5867 net/core/dev.c:5862 net/core/dev.c:6565) > > [ 44.547672] virtnet_poll (drivers/net/virtio_net.c:1427 drivers/net/virtio_net.c:1525) > > [ 44.548251] __napi_poll (net/core/dev.c:6985) > > [ 44.548744] net_rx_action (net/core/dev.c:7054 net/core/dev.c:7139) > > [ 44.549264] __do_softirq (./arch/x86/include/asm/jump_label.h:19 ./include/linux/jump_label.h:200 ./include/trace/events/irq.h:142 kernel/softirq.c:560) > > [ 44.549762] irq_exit_rcu (kernel/softirq.c:433 kernel/softirq.c:637 kernel/softirq.c:649) > > [ 44.551384] common_interrupt (arch/x86/kernel/irq.c:240 (discriminator 13)) > > [ 44.551991] ? asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638) > > [ 44.552654] asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638) > > > > Fixes: fb32856b16ad ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom") > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > Reported-by: Corentin No?l <corentin.noel at collabora.com> > > Tested-by: Corentin No?l <corentin.noel at collabora.com> > > --- > > drivers/net/virtio_net.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index fa407eb8b457..78a01c71a17c 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -406,7 +406,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, > > * add_recvbuf_mergeable() + get_mergeable_buf_len() > > */ > > truesize = headroom ? PAGE_SIZE : truesize; > > - tailroom = truesize - len - headroom; > > + tailroom = truesize - len - headroom - (hdr_padded_len - hdr_len); > > > The patch looks correct and I saw it has been merged. > > But I prefer to do that in receive_big() instead of here. > > ThanksHow? change truesize or headroom? I didn't find a good way. Do you have a good way? Thanks.> > > > > buf = p - headroom; > > > > len -= hdr_len; >
Jason Wang
2021-Jun-04 03:00 UTC
[PATCH net] virtio-net: fix for skb_over_panic inside big mode
? 2021/6/4 ??10:30, Xuan Zhuo ??:> On Fri, 4 Jun 2021 10:28:41 +0800, Jason Wang <jasowang at redhat.com> wrote: >> ? 2021/6/4 ??1:09, Xuan Zhuo ??: >>> In virtio-net's large packet mode, there is a hole in the space behind >>> buf. >> >> before the buf actually or behind the vnet header? >> >> >>> hdr_padded_len - hdr_len >>> >>> We must take this into account when calculating tailroom. >>> >>> [ 44.544385] skb_put.cold (net/core/skbuff.c:5254 (discriminator 1) net/core/skbuff.c:5252 (discriminator 1)) >>> [ 44.544864] page_to_skb (drivers/net/virtio_net.c:485) [ 44.545361] receive_buf (drivers/net/virtio_net.c:849 drivers/net/virtio_net.c:1131) >>> [ 44.545870] ? netif_receive_skb_list_internal (net/core/dev.c:5714) >>> [ 44.546628] ? dev_gro_receive (net/core/dev.c:6103) >>> [ 44.547135] ? napi_complete_done (./include/linux/list.h:35 net/core/dev.c:5867 net/core/dev.c:5862 net/core/dev.c:6565) >>> [ 44.547672] virtnet_poll (drivers/net/virtio_net.c:1427 drivers/net/virtio_net.c:1525) >>> [ 44.548251] __napi_poll (net/core/dev.c:6985) >>> [ 44.548744] net_rx_action (net/core/dev.c:7054 net/core/dev.c:7139) >>> [ 44.549264] __do_softirq (./arch/x86/include/asm/jump_label.h:19 ./include/linux/jump_label.h:200 ./include/trace/events/irq.h:142 kernel/softirq.c:560) >>> [ 44.549762] irq_exit_rcu (kernel/softirq.c:433 kernel/softirq.c:637 kernel/softirq.c:649) >>> [ 44.551384] common_interrupt (arch/x86/kernel/irq.c:240 (discriminator 13)) >>> [ 44.551991] ? asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638) >>> [ 44.552654] asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638) >>> >>> Fixes: fb32856b16ad ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom") >>> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> >>> Reported-by: Corentin No?l <corentin.noel at collabora.com> >>> Tested-by: Corentin No?l <corentin.noel at collabora.com> >>> --- >>> drivers/net/virtio_net.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>> index fa407eb8b457..78a01c71a17c 100644 >>> --- a/drivers/net/virtio_net.c >>> +++ b/drivers/net/virtio_net.c >>> @@ -406,7 +406,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, >>> * add_recvbuf_mergeable() + get_mergeable_buf_len() >>> */ >>> truesize = headroom ? PAGE_SIZE : truesize; >>> - tailroom = truesize - len - headroom; >>> + tailroom = truesize - len - headroom - (hdr_padded_len - hdr_len); >> >> The patch looks correct and I saw it has been merged. >> >> But I prefer to do that in receive_big() instead of here. >> >> Thanks > How? > > change truesize or headroom? > > I didn't find a good way. Do you have a good way?Something like the following? The API is designed to let the caller to pass a correct headroom instead of figure it out by itself. ??????? struct sk_buff *skb ??????????????? page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, true, 0, hdr_padded_len - hdr_len); Thanks> > Thanks. > >> >> >>> buf = p - headroom; >>> >>> len -= hdr_len;