linux-kernel - Re: [syzbot] [net?] KMSAN: uninit-value in __ipv6_addr

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Message-ID: <67b762ef.050a0220.14d86d.02f0.GAE@google.com>
Date: Thu, 20 Feb 2025 09:14:23 -0800
From: syzbot <syzbot+93ab4a777bafb9d9f960@...kaller.appspotmail.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com, 
	eric.dumazet@...il.com, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, maheshb@...gle.com, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] KMSAN: uninit-value in __ipv6_addr_type

syzbot has found a reproducer for the following issue on:

HEAD commit:    87a132e73910 Merge tag 'mm-hotfixes-stable-2025-02-19-17-4..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=109a5498580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8cf1217edc1cc7da
dashboard link: https://syzkaller.appspot.com/bug?extid=93ab4a777bafb9d9f960
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=125b75b0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14433ba4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/21aef40bc697/disk-87a132e7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d449987c6c11/vmlinux-87a132e7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/14c5f26d8765/bzImage-87a132e7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+93ab4a777bafb9d9f960@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47
 __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47
 ipv6_addr_type include/net/ipv6.h:555 [inline]
 ip6_route_output_flags_noref net/ipv6/route.c:2616 [inline]
 ip6_route_output_flags+0x51/0x720 net/ipv6/route.c:2651
 ip6_route_output include/net/ip6_route.h:93 [inline]
 ipvlan_route_v6_outbound+0x24e/0x520 drivers/net/ipvlan/ipvlan_core.c:476
 ipvlan_process_v6_outbound drivers/net/ipvlan/ipvlan_core.c:491 [inline]
 ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:541 [inline]
 ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:605 [inline]
 ipvlan_queue_xmit+0xd72/0x1780 drivers/net/ipvlan/ipvlan_core.c:671
 ipvlan_start_xmit+0x5b/0x210 drivers/net/ipvlan/ipvlan_main.c:223
 __netdev_start_xmit include/linux/netdevice.h:5150 [inline]
 netdev_start_xmit include/linux/netdevice.h:5159 [inline]
 xmit_one net/core/dev.c:3735 [inline]
 dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3751
 __dev_queue_xmit+0x366a/0x57d0 net/core/dev.c:4584
 dev_queue_xmit include/linux/netdevice.h:3311 [inline]
 packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3132 [inline]
 packet_sendmsg+0x93e0/0xa7e0 net/packet/af_packet.c:3164
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:733
 __sys_sendto+0x594/0x750 net/socket.c:2187
 __do_sys_sendto net/socket.c:2194 [inline]
 __se_sys_sendto net/socket.c:2190 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2190
 x64_sys_call+0x346a/0x3c30 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:
 ipvlan_route_v6_outbound+0x18f/0x520 drivers/net/ipvlan/ipvlan_core.c:466
 ipvlan_process_v6_outbound drivers/net/ipvlan/ipvlan_core.c:491 [inline]
 ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:541 [inline]
 ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:605 [inline]
 ipvlan_queue_xmit+0xd72/0x1780 drivers/net/ipvlan/ipvlan_core.c:671
 ipvlan_start_xmit+0x5b/0x210 drivers/net/ipvlan/ipvlan_main.c:223
 __netdev_start_xmit include/linux/netdevice.h:5150 [inline]
 netdev_start_xmit include/linux/netdevice.h:5159 [inline]
 xmit_one net/core/dev.c:3735 [inline]
 dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3751
 __dev_queue_xmit+0x366a/0x57d0 net/core/dev.c:4584
 dev_queue_xmit include/linux/netdevice.h:3311 [inline]
 packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3132 [inline]
 packet_sendmsg+0x93e0/0xa7e0 net/packet/af_packet.c:3164
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:733
 __sys_sendto+0x594/0x750 net/socket.c:2187
 __do_sys_sendto net/socket.c:2194 [inline]
 __se_sys_sendto net/socket.c:2190 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2190
 x64_sys_call+0x346a/0x3c30 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:4121 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 kmem_cache_alloc_node_noprof+0x907/0xe00 mm/slub.c:4216
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:587
 __alloc_skb+0x363/0x7b0 net/core/skbuff.c:678
 alloc_skb include/linux/skbuff.h:1331 [inline]
 alloc_skb_with_frags+0xc8/0xd00 net/core/skbuff.c:6612
 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2897
 packet_alloc_skb net/packet/af_packet.c:2981 [inline]
 packet_snd net/packet/af_packet.c:3075 [inline]
 packet_sendmsg+0x7722/0xa7e0 net/packet/af_packet.c:3164
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:733
 __sys_sendto+0x594/0x750 net/socket.c:2187
 __do_sys_sendto net/socket.c:2194 [inline]
 __se_sys_sendto net/socket.c:2190 [inline]
 __x64_sys_sendto+0x125/0x1d0 net/socket.c:2190
 x64_sys_call+0x346a/0x3c30 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: 5864 Comm: syz-executor285 Not tainted 6.14.0-rc3-syzkaller-00079-g87a132e73910 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
=====================================================


---
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#syz test: git://repo/address.git branch-or-commit-hash
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