5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit 3a3be7ff9224f424e485287b54be00d2c6bd9c40 upstream.
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+0x3799/0x3c10 arch/x86/include/generated/asm/syscalls_64.h:45 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was created at: slab_post_alloc_hook mm/slub.c:3994 [inline] slab_alloc_node mm/slub.c:4037 [inline] kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4080 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:583 __alloc_skb+0x363/0x7b0 net/core/skbuff.c:674 alloc_skb include/linux/skbuff.h:1320 [inline] alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6526 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2815 packet_alloc_skb net/packet/af_packet.c:2994 [inline] packet_snd net/packet/af_packet.c:3088 [inline] packet_sendmsg+0x749c/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+0x3799/0x3c10 arch/x86/include/generated/asm/syscalls_64.h:45 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
CPU: 0 UID: 0 PID: 7115 Comm: syz.1.515 Not tainted 6.11.0-rc1-syzkaller-00043-g94ede2a3e913 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Fixes: 999cb275c807 ("gtp: add IPv6 support") Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Harald Welte laforge@gnumonks.org Reviewed-by: Pablo Neira Ayuso pablo@netfilter.org Link: https://patch.msgid.link/20240808132455.3413916-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/gtp.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -573,6 +573,9 @@ static netdev_tx_t gtp_dev_xmit(struct s if (skb_cow_head(skb, dev->needed_headroom)) goto tx_err;
+ if (!pskb_inet_may_pull(skb)) + goto tx_err; + skb_reset_inner_headers(skb);
/* PDP context lookups in gtp_build_skb_*() need rcu read-side lock. */