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geneve: fix header validation in geneve[6]_xmit_skb

Antoine Tenart requested to merge atenart/centos-stream-9:c9s/RHEL-37386/geneve-vlan-fix into main

JIRA: https://issues.redhat.com/browse/RHEL-37386
Upstream Status: linux.git
CVE: CVE-2024-35973

commit d8a6213d70accb403b82924a1c229e733433a5ef
Author: Eric Dumazet edumazet@google.com
Date: Fri Apr 5 10:30:34 2024 +0000

geneve: fix header validation in geneve[6]_xmit_skb  

syzbot is able to trigger an uninit-value in geneve_xmit() [1]  

Problem : While most ip tunnel helpers (like ip_tunnel_get_dsfield())  
uses skb_protocol(skb, true), pskb_inet_may_pull() is only using  
skb->protocol.  

If anything else than ETH_P_IPV6 or ETH_P_IP is found in skb->protocol,  
pskb_inet_may_pull() does nothing at all.  

If a vlan tag was provided by the caller (af_packet in the syzbot case),  
the network header might not point to the correct location, and skb  
linear part could be smaller than expected.  

Add skb_vlan_inet_prepare() to perform a complete mac validation.  

Use this in geneve for the moment, I suspect we need to adopt this  
more broadly.  

v4 - Jakub reported v3 broke l2_tos_ttl_inherit.sh selftest  
   - Only call __vlan_get_protocol() for vlan types.  
Link: https://lore.kernel.org/netdev/20240404100035.3270a7d5@kernel.org/  

v2,v3 - Addressed Sabrina comments on v1 and v2  
Link: https://lore.kernel.org/netdev/Zg1l9L2BNoZWZDZG@hog/  

[1]  

BUG: KMSAN: uninit-value in geneve_xmit_skb drivers/net/geneve.c:910 [inline]  
 BUG: KMSAN: uninit-value in geneve_xmit+0x302d/0x5420 drivers/net/geneve.c:1030  
  geneve_xmit_skb drivers/net/geneve.c:910 [inline]  
  geneve_xmit+0x302d/0x5420 drivers/net/geneve.c:1030  
  __netdev_start_xmit include/linux/netdevice.h:4903 [inline]  
  netdev_start_xmit include/linux/netdevice.h:4917 [inline]  
  xmit_one net/core/dev.c:3531 [inline]  
  dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547  
  __dev_queue_xmit+0x348d/0x52c0 net/core/dev.c:4335  
  dev_queue_xmit include/linux/netdevice.h:3091 [inline]  
  packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276  
  packet_snd net/packet/af_packet.c:3081 [inline]  
  packet_sendmsg+0x8bb0/0x9ef0 net/packet/af_packet.c:3113  
  sock_sendmsg_nosec net/socket.c:730 [inline]  
  __sock_sendmsg+0x30f/0x380 net/socket.c:745  
  __sys_sendto+0x685/0x830 net/socket.c:2191  
  __do_sys_sendto net/socket.c:2203 [inline]  
  __se_sys_sendto net/socket.c:2199 [inline]  
  __x64_sys_sendto+0x125/0x1d0 net/socket.c:2199  
 do_syscall_64+0xd5/0x1f0  
 entry_SYSCALL_64_after_hwframe+0x6d/0x75  

Uninit was created at:  
  slab_post_alloc_hook mm/slub.c:3804 [inline]  
  slab_alloc_node mm/slub.c:3845 [inline]  
  kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888  
  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577  
  __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668  
  alloc_skb include/linux/skbuff.h:1318 [inline]  
  alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504  
  sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795  
  packet_alloc_skb net/packet/af_packet.c:2930 [inline]  
  packet_snd net/packet/af_packet.c:3024 [inline]  
  packet_sendmsg+0x722d/0x9ef0 net/packet/af_packet.c:3113  
  sock_sendmsg_nosec net/socket.c:730 [inline]  
  __sock_sendmsg+0x30f/0x380 net/socket.c:745  
  __sys_sendto+0x685/0x830 net/socket.c:2191  
  __do_sys_sendto net/socket.c:2203 [inline]  
  __se_sys_sendto net/socket.c:2199 [inline]  
  __x64_sys_sendto+0x125/0x1d0 net/socket.c:2199  
 do_syscall_64+0xd5/0x1f0  
 entry_SYSCALL_64_after_hwframe+0x6d/0x75  

CPU: 0 PID: 5033 Comm: syz-executor346 Not tainted 6.9.0-rc1-syzkaller-00005-g928a87efa423 #0  
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024  

Fixes: d13f048dd40e ("net: geneve: modify IP header check in geneve6_xmit_skb and geneve_xmit_skb")  
Reported-by: syzbot+9ee20ec1de7b3168db09@syzkaller.appspotmail.com  
Closes: https://lore.kernel.org/netdev/000000000000d19c3a06152f9ee4@google.com/  
Signed-off-by: Eric Dumazet <edumazet@google.com>  
Cc: Phillip Potter <phil@philpotter.co.uk>  
Cc: Sabrina Dubroca <sd@queasysnail.net>  
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>  
Reviewed-by: Phillip Potter <phil@philpotter.co.uk>  
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Antoine Tenart atenart@redhat.com

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