2023-10-07 00:51:54

by Ma Ke

Subject: [PATCH] um: vector: fix return value check in vector_mmsg_rx

In vector_mmsg_rx, to avoid an unexpected result returned by
pskb_trim, we should check the return value of pskb_trim().

Signed-off-by: Ma Ke <[email protected]>
---
arch/um/drivers/vector_kern.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 131b7cb29576..c280ce5ea6ce 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -1013,8 +1013,8 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget)
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
}
- pskb_trim(skb,
- mmsg_vector->msg_len - vp->rx_header_size);
+ if (pskb_trim(skb, mmsg_vector->msg_len - vp->rx_header_size))
+ return 0;
skb->protocol = eth_type_trans(skb, skb->dev);
/*
* We do not need to lock on updating stats here
--
2.37.2

2023-10-07 06:13:27

by Anton Ivanov

Subject: Re: [PATCH] um: vector: fix return value check in vector_mmsg_rx

On 07/10/2023 01:51, Ma Ke wrote:
> In vector_mmsg_rx, to avoid an unexpected result returned by
> pskb_trim, we should check the return value of pskb_trim().
>
> Signed-off-by: Ma Ke <[email protected]>
> ---
> arch/um/drivers/vector_kern.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
> index 131b7cb29576..c280ce5ea6ce 100644
> --- a/arch/um/drivers/vector_kern.c
> +++ b/arch/um/drivers/vector_kern.c
> @@ -1013,8 +1013,8 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget)
> skb->ip_summed = CHECKSUM_UNNECESSARY;
> }
> }
> - pskb_trim(skb,
> - mmsg_vector->msg_len - vp->rx_header_size);
> + if (pskb_trim(skb, mmsg_vector->msg_len - vp->rx_header_size))
> + return 0;
> skb->protocol = eth_type_trans(skb, skb->dev);
> /*
> * We do not need to lock on updating stats here

That does not look right. You can have errors when processing an
individual packet. That is not a reason to bail and you should process
the next ones. This way you just dropped the rest of the RX vector (up
to 64 packets at default settings).

--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/

2023-10-09 07:32:26

by Johannes Berg

Subject: Re: [PATCH] um: vector: fix return value check in vector_mmsg_rx

On Sat, 2023-10-07 at 08:51 +0800, Ma Ke wrote:
> In vector_mmsg_rx, to avoid an unexpected result returned by
> pskb_trim, we should check the return value of pskb_trim().

And how exactly do you propose pskb_trim() will return anything but 0 in
this scenario?

Please. If you have a static checker, _think_ about it's output before
blindly sending patches.

johannes