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b=fW+H5sReHMsLNQlK2y3rT3QZGkvKbw1Mb+iwTO3Pjlkn8SqdCO+FKIbHG+oVORnz8jhV5E xttJT3L6Fj5grTBQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 3F0F74A0B0; Wed, 1 Apr 2026 14:50:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id VHSADMEwzWnSGwAAD6G6ig (envelope-from ); Wed, 01 Apr 2026 14:50:41 +0000 Message-ID: <17d4d7e2-3b55-4eac-926c-e1355fbc1cd3@suse.de> Date: Wed, 1 Apr 2026 16:50:36 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2 net v2] ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop() To: netdev@vger.kernel.org Cc: idosch@nvidia.com, petrm@nvidia.com, horms@kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, dsahern@kernel.org, kees@kernel.org, Yiming Qian References: <20260401081741.4273-1-fmancera@suse.de> <20260401081741.4273-2-fmancera@suse.de> Content-Language: en-US From: Fernando Fernandez Mancera In-Reply-To: <20260401081741.4273-2-fmancera@suse.de> Content-Type: text/plain; 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RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:mid,suse.de:dkim,suse.de:email] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: D55605BD8A On 4/1/26 10:17 AM, Fernando Fernandez Mancera wrote: > When querying a nexthop object via RTM_GETNEXTHOP, the kernel currently > allocates a fixed-size skb using NLMSG_GOODSIZE. While sufficient for > single nexthops and small Equal-Cost Multi-Path groups, this fixed > allocation fails for large nexthop groups like 512 nexthops. > > This results in the following warning splat: > > WARNING: net/ipv4/nexthop.c:3395 at rtm_get_nexthop+0x176/0x1c0, CPU#20: rep/4608 > [...] > RIP: 0010:rtm_get_nexthop (net/ipv4/nexthop.c:3395) > [...] > Call Trace: > > rtnetlink_rcv_msg (net/core/rtnetlink.c:6989) > netlink_rcv_skb (net/netlink/af_netlink.c:2550) > netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344) > netlink_sendmsg (net/netlink/af_netlink.c:1894) > ____sys_sendmsg (net/socket.c:721 net/socket.c:736 net/socket.c:2585) > ___sys_sendmsg (net/socket.c:2641) > __sys_sendmsg (net/socket.c:2671) > do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > > > Fix this by allocating the size dynamically using nh_nlmsg_size() and > using nlmsg_new(), this is consistent with nexthop_notify() behavior. In > addition, adjust nh_nlmsg_size_grp() so it calculates the size needed > based on flags passed. > > This cannot be reproduced via iproute2 as the group size is currently > limited and the command fails as follows: > > addattr_l ERROR: message exceeded bound of 1048 > > Fixes: 430a049190de ("nexthop: Add support for nexthop groups") > Reported-by: Yiming Qian > Closes: https://lore.kernel.org/netdev/CAL_bE8Li2h4KO+AQFXW4S6Yb_u5X4oSKnkywW+LPFjuErhqELA@mail.gmail.com/ > Signed-off-by: Fernando Fernandez Mancera As Ido requested some changes, update the status in patchwork. -- pw-bot: cr