* [PATCH net] ionic: linearize tso skb with too many frags
@ 2021-03-16 18:52 Shannon Nelson
2021-03-16 21:54 ` Jakub Kicinski
0 siblings, 1 reply; 3+ messages in thread
From: Shannon Nelson @ 2021-03-16 18:52 UTC (permalink / raw)
To: netdev, davem, kuba; +Cc: drivers, Shannon Nelson
We were linearizing non-TSO skbs that had too many frags, but
we weren't checking number of frags on TSO skbs. This could
lead to a bad page reference when we received a TSO skb with
more frags than the Tx descriptor could support.
Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
---
.../net/ethernet/pensando/ionic/ionic_txrx.c | 28 ++++++++++---------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 162a1ff1e9d2..462b0d106be4 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -1079,25 +1079,27 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
{
int sg_elems = q->lif->qtype_info[IONIC_QTYPE_TXQ].max_sg_elems;
struct ionic_tx_stats *stats = q_to_tx_stats(q);
+ int ndescs;
int err;
- /* If TSO, need roundup(skb->len/mss) descs */
+ /* If TSO, need roundup(skb->len/mss) descs
+ * If non-TSO, just need 1 desc and nr_frags sg elems
+ */
if (skb_is_gso(skb))
- return (skb->len / skb_shinfo(skb)->gso_size) + 1;
+ ndescs = (skb->len / skb_shinfo(skb)->gso_size) + 1;
+ else
+ ndescs = 1;
- /* If non-TSO, just need 1 desc and nr_frags sg elems */
- if (skb_shinfo(skb)->nr_frags <= sg_elems)
- return 1;
+ /* If too many frags, linearize */
+ if (skb_shinfo(skb)->nr_frags > sg_elems) {
+ err = skb_linearize(skb);
+ if (err)
+ return err;
- /* Too many frags, so linearize */
- err = skb_linearize(skb);
- if (err)
- return err;
-
- stats->linearize++;
+ stats->linearize++;
+ }
- /* Need 1 desc and zero sg elems */
- return 1;
+ return ndescs;
}
static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs)
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net] ionic: linearize tso skb with too many frags
2021-03-16 18:52 [PATCH net] ionic: linearize tso skb with too many frags Shannon Nelson
@ 2021-03-16 21:54 ` Jakub Kicinski
2021-03-16 23:24 ` Shannon Nelson
0 siblings, 1 reply; 3+ messages in thread
From: Jakub Kicinski @ 2021-03-16 21:54 UTC (permalink / raw)
To: Shannon Nelson; +Cc: netdev, davem, drivers
On Tue, 16 Mar 2021 11:52:43 -0700 Shannon Nelson wrote:
> We were linearizing non-TSO skbs that had too many frags, but
> we weren't checking number of frags on TSO skbs. This could
> lead to a bad page reference when we received a TSO skb with
> more frags than the Tx descriptor could support.
>
> Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
> Signed-off-by: Shannon Nelson <snelson@pensando.io>
> ---
> .../net/ethernet/pensando/ionic/ionic_txrx.c | 28 ++++++++++---------
> 1 file changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
> index 162a1ff1e9d2..462b0d106be4 100644
> --- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
> +++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
> @@ -1079,25 +1079,27 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
> {
> int sg_elems = q->lif->qtype_info[IONIC_QTYPE_TXQ].max_sg_elems;
> struct ionic_tx_stats *stats = q_to_tx_stats(q);
> + int ndescs;
> int err;
>
> - /* If TSO, need roundup(skb->len/mss) descs */
> + /* If TSO, need roundup(skb->len/mss) descs
> + * If non-TSO, just need 1 desc and nr_frags sg elems
> + */
> if (skb_is_gso(skb))
> - return (skb->len / skb_shinfo(skb)->gso_size) + 1;
> + ndescs = (skb->len / skb_shinfo(skb)->gso_size) + 1;
Slightly unrelated but why not gso_segs? len / gso_size + 1 could be
over counting, not to mention that div is expensive.
Are you segmenting in the driver? Why do you need #segs descriptors?
> + else
> + ndescs = 1;
>
> - /* If non-TSO, just need 1 desc and nr_frags sg elems */
> - if (skb_shinfo(skb)->nr_frags <= sg_elems)
> - return 1;
> + /* If too many frags, linearize */
> + if (skb_shinfo(skb)->nr_frags > sg_elems) {
> + err = skb_linearize(skb);
> + if (err)
> + return err;
>
> - /* Too many frags, so linearize */
> - err = skb_linearize(skb);
> - if (err)
> - return err;
> -
> - stats->linearize++;
> + stats->linearize++;
> + }
>
> - /* Need 1 desc and zero sg elems */
> - return 1;
> + return ndescs;
I'd be tempted to push back on the refactoring here, you could've
just replaced return 1;s with return ndescs;s without changing
the indentation.. this will give all backporters a pause. But
not the end of the world, I guess.
> }
>
> static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] ionic: linearize tso skb with too many frags
2021-03-16 21:54 ` Jakub Kicinski
@ 2021-03-16 23:24 ` Shannon Nelson
0 siblings, 0 replies; 3+ messages in thread
From: Shannon Nelson @ 2021-03-16 23:24 UTC (permalink / raw)
To: Jakub Kicinski; +Cc: netdev, davem, drivers
On 3/16/21 2:54 PM, Jakub Kicinski wrote:
> On Tue, 16 Mar 2021 11:52:43 -0700 Shannon Nelson wrote:
>> We were linearizing non-TSO skbs that had too many frags, but
>> we weren't checking number of frags on TSO skbs. This could
>> lead to a bad page reference when we received a TSO skb with
>> more frags than the Tx descriptor could support.
>>
>> Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
>> Signed-off-by: Shannon Nelson <snelson@pensando.io>
>> ---
>> .../net/ethernet/pensando/ionic/ionic_txrx.c | 28 ++++++++++---------
>> 1 file changed, 15 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
>> index 162a1ff1e9d2..462b0d106be4 100644
>> --- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
>> +++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
>> @@ -1079,25 +1079,27 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
>> {
>> int sg_elems = q->lif->qtype_info[IONIC_QTYPE_TXQ].max_sg_elems;
>> struct ionic_tx_stats *stats = q_to_tx_stats(q);
>> + int ndescs;
>> int err;
>>
>> - /* If TSO, need roundup(skb->len/mss) descs */
>> + /* If TSO, need roundup(skb->len/mss) descs
>> + * If non-TSO, just need 1 desc and nr_frags sg elems
>> + */
>> if (skb_is_gso(skb))
>> - return (skb->len / skb_shinfo(skb)->gso_size) + 1;
>> + ndescs = (skb->len / skb_shinfo(skb)->gso_size) + 1;
> Slightly unrelated but why not gso_segs? len / gso_size + 1 could be
> over counting, not to mention that div is expensive.
Good catch - we can probably do that.
>
> Are you segmenting in the driver? Why do you need #segs descriptors?
The device needs each descriptor to be no more than mss length, so there
might be a number of descriptors for a large packet.
>
>> + else
>> + ndescs = 1;
>>
>> - /* If non-TSO, just need 1 desc and nr_frags sg elems */
>> - if (skb_shinfo(skb)->nr_frags <= sg_elems)
>> - return 1;
>> + /* If too many frags, linearize */
>> + if (skb_shinfo(skb)->nr_frags > sg_elems) {
>> + err = skb_linearize(skb);
>> + if (err)
>> + return err;
>>
>> - /* Too many frags, so linearize */
>> - err = skb_linearize(skb);
>> - if (err)
>> - return err;
>> -
>> - stats->linearize++;
>> + stats->linearize++;
>> + }
>>
>> - /* Need 1 desc and zero sg elems */
>> - return 1;
>> + return ndescs;
> I'd be tempted to push back on the refactoring here, you could've
> just replaced return 1;s with return ndescs;s without changing
> the indentation.. this will give all backporters a pause. But
> not the end of the world, I guess.
I can tweak that a little.
I'll send a v2.
sln
>
>> }
>>
>> static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs)
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-03-16 23:25 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-03-16 18:52 [PATCH net] ionic: linearize tso skb with too many frags Shannon Nelson
2021-03-16 21:54 ` Jakub Kicinski
2021-03-16 23:24 ` Shannon Nelson
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