* [PATCH net] net: test tailroom before appending to linear skb
@ 2018-05-17 15:54 Willem de Bruijn
2018-05-17 16:05 ` Eric Dumazet
2018-05-17 16:44 ` Eric Dumazet
0 siblings, 2 replies; 4+ messages in thread
From: Willem de Bruijn @ 2018-05-17 15:54 UTC (permalink / raw)
To: netdev; +Cc: davem, Willem de Bruijn
From: Willem de Bruijn <willemb@google.com>
Device features may change during transmission. In particular with
corking, a device may toggle scatter-gather in between allocating
and writing to an skb.
Do not unconditionally assume that !NETIF_F_SG at write time implies
that the same held at alloc time and thus the skb has sufficient
tailroom.
This issue predates git history.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
---
net/ipv4/ip_output.c | 3 ++-
net/ipv6/ip6_output.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 83c73bab2c3d..c15204ec2eb0 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1045,7 +1045,8 @@ static int __ip_append_data(struct sock *sk,
if (copy > length)
copy = length;
- if (!(rt->dst.dev->features&NETIF_F_SG)) {
+ if (!(rt->dst.dev->features&NETIF_F_SG) &&
+ skb_tailroom(skb) > copy) {
unsigned int off;
off = skb->len;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 2e891d2c30ef..7b6d1689087b 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1503,7 +1503,8 @@ static int __ip6_append_data(struct sock *sk,
if (copy > length)
copy = length;
- if (!(rt->dst.dev->features&NETIF_F_SG)) {
+ if (!(rt->dst.dev->features&NETIF_F_SG) &&
+ skb_tailroom(skb) >= copy) {
unsigned int off;
off = skb->len;
--
2.17.0.441.gb46fe60e1d-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH net] net: test tailroom before appending to linear skb
2018-05-17 15:54 [PATCH net] net: test tailroom before appending to linear skb Willem de Bruijn
@ 2018-05-17 16:05 ` Eric Dumazet
2018-05-17 16:44 ` Eric Dumazet
1 sibling, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2018-05-17 16:05 UTC (permalink / raw)
To: Willem de Bruijn, netdev; +Cc: davem, Willem de Bruijn
On 05/17/2018 08:54 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@google.com>
>
> Device features may change during transmission. In particular with
> corking, a device may toggle scatter-gather in between allocating
> and writing to an skb.
>
> Do not unconditionally assume that !NETIF_F_SG at write time implies
> that the same held at alloc time and thus the skb has sufficient
> tailroom.
>
> This issue predates git history.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
Excellent, thanks Willem.
Reviewed-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] net: test tailroom before appending to linear skb
2018-05-17 15:54 [PATCH net] net: test tailroom before appending to linear skb Willem de Bruijn
2018-05-17 16:05 ` Eric Dumazet
@ 2018-05-17 16:44 ` Eric Dumazet
2018-05-17 17:03 ` Willem de Bruijn
1 sibling, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2018-05-17 16:44 UTC (permalink / raw)
To: Willem de Bruijn, netdev; +Cc: davem, Willem de Bruijn
On 05/17/2018 08:54 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@google.com>
>
> Device features may change during transmission. In particular with
> corking, a device may toggle scatter-gather in between allocating
> and writing to an skb.
>
> Do not unconditionally assume that !NETIF_F_SG at write time implies
> that the same held at alloc time and thus the skb has sufficient
> tailroom.
>
> This issue predates git history.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> ---
> net/ipv4/ip_output.c | 3 ++-
> net/ipv6/ip6_output.c | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 83c73bab2c3d..c15204ec2eb0 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -1045,7 +1045,8 @@ static int __ip_append_data(struct sock *sk,
> if (copy > length)
> copy = length;
>
> - if (!(rt->dst.dev->features&NETIF_F_SG)) {
> + if (!(rt->dst.dev->features&NETIF_F_SG) &&
> + skb_tailroom(skb) > copy) {
On second thought, maybe use >= for the test ?
> unsigned int off;
>
> off = skb->len;
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 2e891d2c30ef..7b6d1689087b 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1503,7 +1503,8 @@ static int __ip6_append_data(struct sock *sk,
> if (copy > length)
> copy = length;
>
> - if (!(rt->dst.dev->features&NETIF_F_SG)) {
> + if (!(rt->dst.dev->features&NETIF_F_SG) &&
> + skb_tailroom(skb) >= copy) {
> unsigned int off;
>
> off = skb->len;
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] net: test tailroom before appending to linear skb
2018-05-17 16:44 ` Eric Dumazet
@ 2018-05-17 17:03 ` Willem de Bruijn
0 siblings, 0 replies; 4+ messages in thread
From: Willem de Bruijn @ 2018-05-17 17:03 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Network Development, David Miller, Willem de Bruijn
On Thu, May 17, 2018 at 12:44 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
>
> On 05/17/2018 08:54 AM, Willem de Bruijn wrote:
>> From: Willem de Bruijn <willemb@google.com>
>>
>> Device features may change during transmission. In particular with
>> corking, a device may toggle scatter-gather in between allocating
>> and writing to an skb.
>>
>> Do not unconditionally assume that !NETIF_F_SG at write time implies
>> that the same held at alloc time and thus the skb has sufficient
>> tailroom.
>>
>> This issue predates git history.
>>
>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>> Reported-by: Eric Dumazet <edumazet@google.com>
>> Signed-off-by: Willem de Bruijn <willemb@google.com>
>> ---
>> net/ipv4/ip_output.c | 3 ++-
>> net/ipv6/ip6_output.c | 3 ++-
>> 2 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
>> index 83c73bab2c3d..c15204ec2eb0 100644
>> --- a/net/ipv4/ip_output.c
>> +++ b/net/ipv4/ip_output.c
>> @@ -1045,7 +1045,8 @@ static int __ip_append_data(struct sock *sk,
>> if (copy > length)
>> copy = length;
>>
>> - if (!(rt->dst.dev->features&NETIF_F_SG)) {
>> + if (!(rt->dst.dev->features&NETIF_F_SG) &&
>> + skb_tailroom(skb) > copy) {
>
> On second thought, maybe use >= for the test ?
Ai, yes of course. Will send a v2.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-05-17 17:04 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2018-05-17 15:54 [PATCH net] net: test tailroom before appending to linear skb Willem de Bruijn
2018-05-17 16:05 ` Eric Dumazet
2018-05-17 16:44 ` Eric Dumazet
2018-05-17 17:03 ` Willem de Bruijn
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