[syzbot] [netfilter?] KMSAN: uninit-value in ip6table_mangle_hook (3)

[syzbot <syzbot+6023ea32e206eef7920a@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    2e1b3cc9d7f7 Merge tag 'arm-fixes-6.12-2' of git://git.ker..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=105e0d87980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fdf74cce377223b
dashboard link: https://syzkaller.appspot.com/bug?extid=6023ea32e206eef7920a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=165d5d5f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=145e0d87980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/08456e37db58/disk-2e1b3cc9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cc957f7ba80b/vmlinux-2e1b3cc9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7579fe72ed89/bzImage-2e1b3cc9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6023ea32e206eef7920a@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in ip6t_mangle_out net/ipv6/netfilter/ip6table_mangle.c:56 [inline]
BUG: KMSAN: uninit-value in ip6table_mangle_hook+0x97d/0x9c0 net/ipv6/netfilter/ip6table_mangle.c:72
 ip6t_mangle_out net/ipv6/netfilter/ip6table_mangle.c:56 [inline]
 ip6table_mangle_hook+0x97d/0x9c0 net/ipv6/netfilter/ip6table_mangle.c:72
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:269 [inline]
 __ip6_local_out+0x5ac/0x640 net/ipv6/output_core.c:143
 ip6_local_out+0x4c/0x210 net/ipv6/output_core.c:153
 ip6tunnel_xmit+0x129/0x460 include/net/ip6_tunnel.h:161
 ip6_tnl_xmit+0x341a/0x3860 net/ipv6/ip6_tunnel.c:1281
 __gre6_xmit+0x14b9/0x1550 net/ipv6/ip6_gre.c:815
 ip6gre_xmit_ipv4 net/ipv6/ip6_gre.c:839 [inline]
 ip6gre_tunnel_xmit+0x18f7/0x2030 net/ipv6/ip6_gre.c:922
 __netdev_start_xmit include/linux/netdevice.h:4928 [inline]
 netdev_start_xmit include/linux/netdevice.h:4937 [inline]
 xmit_one net/core/dev.c:3588 [inline]
 dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3604
 sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343
 __dev_xmit_skb net/core/dev.c:3825 [inline]
 __dev_queue_xmit+0x2fcf/0x56d0 net/core/dev.c:4398
 dev_queue_xmit include/linux/netdevice.h:3094 [inline]
 packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3145 [inline]
 packet_sendmsg+0x908b/0xa370 net/packet/af_packet.c:3177
 sock_sendmsg_nosec net/socket.c:729 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:744
 __sys_sendto+0x645/0x7f0 net/socket.c:2214
 __do_sys_sendto net/socket.c:2226 [inline]
 __se_sys_sendto net/socket.c:2222 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2222
 x64_sys_call+0x3373/0x3ba0 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 stored to memory at:
 ip6_tnl_xmit+0x34f7/0x3860 net/ipv6/ip6_tunnel.c:1277
 __gre6_xmit+0x14b9/0x1550 net/ipv6/ip6_gre.c:815
 ip6gre_xmit_ipv4 net/ipv6/ip6_gre.c:839 [inline]
 ip6gre_tunnel_xmit+0x18f7/0x2030 net/ipv6/ip6_gre.c:922
 __netdev_start_xmit include/linux/netdevice.h:4928 [inline]
 netdev_start_xmit include/linux/netdevice.h:4937 [inline]
 xmit_one net/core/dev.c:3588 [inline]
 dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3604
 sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343
 __dev_xmit_skb net/core/dev.c:3825 [inline]
 __dev_queue_xmit+0x2fcf/0x56d0 net/core/dev.c:4398
 dev_queue_xmit include/linux/netdevice.h:3094 [inline]
 packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3145 [inline]
 packet_sendmsg+0x908b/0xa370 net/packet/af_packet.c:3177
 sock_sendmsg_nosec net/socket.c:729 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:744
 __sys_sendto+0x645/0x7f0 net/socket.c:2214
 __do_sys_sendto net/socket.c:2226 [inline]
 __se_sys_sendto net/socket.c:2222 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2222
 x64_sys_call+0x3373/0x3ba0 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:4091 [inline]
 slab_alloc_node mm/slub.c:4134 [inline]
 __do_kmalloc_node mm/slub.c:4263 [inline]
 __kmalloc_node_track_caller_noprof+0x6c7/0xf90 mm/slub.c:4283
 kmalloc_reserve+0x23e/0x4a0 net/core/skbuff.c:609
 pskb_expand_head+0x226/0x1a60 net/core/skbuff.c:2275
 skb_realloc_headroom+0x140/0x2b0 net/core/skbuff.c:2355
 ip6_tnl_xmit+0x2106/0x3860 net/ipv6/ip6_tunnel.c:1227
 __gre6_xmit+0x14b9/0x1550 net/ipv6/ip6_gre.c:815
 ip6gre_xmit_ipv4 net/ipv6/ip6_gre.c:839 [inline]
 ip6gre_tunnel_xmit+0x18f7/0x2030 net/ipv6/ip6_gre.c:922
 __netdev_start_xmit include/linux/netdevice.h:4928 [inline]
 netdev_start_xmit include/linux/netdevice.h:4937 [inline]
 xmit_one net/core/dev.c:3588 [inline]
 dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3604
 sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343
 __dev_xmit_skb net/core/dev.c:3825 [inline]
 __dev_queue_xmit+0x2fcf/0x56d0 net/core/dev.c:4398
 dev_queue_xmit include/linux/netdevice.h:3094 [inline]
 packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3145 [inline]
 packet_sendmsg+0x908b/0xa370 net/packet/af_packet.c:3177
 sock_sendmsg_nosec net/socket.c:729 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:744
 __sys_sendto+0x645/0x7f0 net/socket.c:2214
 __do_sys_sendto net/socket.c:2226 [inline]
 __se_sys_sendto net/socket.c:2222 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2222
 x64_sys_call+0x3373/0x3ba0 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: 1 UID: 0 PID: 5819 Comm: syz-executor359 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
=====================================================


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