Messages in this thread | | | Date | Thu, 24 Feb 2022 09:08:35 -0800 | From | Jakub Kicinski <> | Subject | Re: [PATCH] net:fix up skbs delta_truesize in UDP GRO frag_list |
| |
On Wed, 23 Feb 2022 18:08:47 +0800 lena.wang wrote: > The truesize for a UDP GRO packet is added by main skb and skbs in main > skb's frag_list: > skb_gro_receive_list > p->truesize += skb->truesize; > > When uncloning skb, it will call pskb_expand_head and trusesize for > frag_list skbs may increase. This can occur when allocators uses > __netdev_alloc_skb and not jump into __alloc_skb. This flow does not > use ksize(len) to calculate truesize while pskb_expand_head uses. > skb_segment_list > err = skb_unclone(nskb, GFP_ATOMIC); > pskb_expand_head > if (!skb->sk || skb->destructor == sock_edemux) > skb->truesize += size - osize; > > If we uses increased truesize adding as delta_truesize, it will be > larger than before and even larger than previous total truesize value > if skbs in frag_list are abundant. The main skb truesize will become > smaller and even a minus value or a huge value for an unsigned int > parameter. Then the following memory check will drop this abnormal skb. > > To avoid this error we should use the original truesize to segment the > main skb. > > Signed-off-by: lena wang <lena.wang@mediatek.com>
CC: Eric
| |