Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

gtp: pull network headers in gtp_dev_xmit()

syzbot/KMSAN reported use of uninit-value in get_dev_xmit() [1]

We must make sure the IPv4 or Ipv6 header is pulled in skb->head before accessing fields in them.

Use pskb_inet_may_pull() to fix this issue.

[1] BUG: KMSAN: uninit-value in ipv6_pdp_find drivers/net/gtp.c:220 [inline] BUG: KMSAN: uninit-value in gtp_build_skb_ip6 drivers/net/gtp.c:1229 [inline] BUG: KMSAN: uninit-value in gtp_dev_xmit+0x1424/0x2540 drivers/net/gtp.c:1281 ipv6_pdp_find drivers/net/gtp.c:220 [inline] gtp_build_skb_ip6 drivers/net/gtp.c:1229 [inline] gtp_dev_xmit+0x1424/0x2540 drivers/net/gtp.c:1281 __netdev_start_xmit include/linux/netdevice.h:4913 [inline] netdev_start_xmit include/linux/netdevice.h:4922 [inline] xmit_one net/core/dev.c:3580 [inline] dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3596 __dev_queue_xmit+0x358c/0x5610 net/core/dev.c:4423 dev_queue_xmit include/linux/netdevice.h:3105 [inline] packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3145 [inline] packet_sendmsg+0x90e3/0xa3a0 net/packet/af_packet.c:3177 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:745 __sys_sendto+0x685/0x830 net/socket.c:2204 __do_sys_sendto net/socket.c:2216 [inline] __se_sys_sendto net/socket.c:2212 [inline] __x64_sys_sendto+0x125/0x1d0 net/socket.c:2212 x64_sys_call+0x3799/0x3c…