Re: [PATCH] net: drop skbs in napi->rx_list when removing the napi context.
From: Eric Dumazet <hidden>
Date: 2021-08-13 10:16:49
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bpf, lkml, netdev
On 8/12/21 9:17 PM, Phi Nguyen wrote:
On 8/12/2021 3:07 PM, Eric Dumazet wrote:quoted
Also I object to this fix. If packets have been stored temporarily in GRO, they should be released at some point, normally at the end of a napi poll. By released, I mean that these packets should reach the upper stack, instead of being dropped without any notification. It seems a call to gro_normal_list() is missing somewhere. Can you find where ? Thanks ! H Eric,I think the location that should have a call to gro_normal_list() is __netif_napi_del(). Let say, if the driver call a function that lead to gro_normal_one(), and add a skb to the rx_list while the napi poll is not scheduled, and the driver remove the napi context before a napi poll could be triggered, then the added skb will be lost. Actually, this was the first solution that I tried with syzbot (It passed the test too). Best regards, Phi
I think the real bug is in drivers/net/tun.c It can call napi_gro_frags() and I do not see corresponding napi_complete() This seems completely bogus. Your patch only works around one the many bugs caused by commit 90e33d45940793def6f773b2d528e9f3c84ffdc7 tun: enable napi_gro_frags() for TUN/TAP driver I suggest not adding your patch, because we should fix the root cause. _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees