Re: [syzbot] [net?] upstream test error: KMSAN: use-after-free in mctp_dump_addrinfo

From: syzbot
Date: Mon May 05 2025 - 04:19:53 EST

> #syz dup: [syzbot] [net?] upstream test error: KMSAN: uninit-value in

can't find the dup bug

> mctp_dump_addrinfo
>
> On Thu, 2025-05-01 at 04:15 -0700, syzbot wrote:
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: 4f79eaa2ceac kbuild: Properly disable -Wunterminated-strin..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=15bc71b3980000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=53c85d265a8f3692
>> dashboard link: https://syzkaller.appspot.com/bug?extid=1065a199625a388fce60
>> compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/3594998c29f0/disk-4f79eaa2.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/2cd908ac5281/vmlinux-4f79eaa2.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/5ea15b7bacde/bzImage-4f79eaa2.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+1065a199625a388fce60@xxxxxxxxxxxxxxxxxxxxxxxxx
>>
>> =====================================================
>> BUG: KMSAN: use-after-free in mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
>> mctp_dump_addrinfo+0x208/0xac0 net/mctp/device.c:128
>> rtnl_dump_all+0x3ec/0x5b0 net/core/rtnetlink.c:4380
>> rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6824
>> netlink_dump+0x97b/0x1690 net/netlink/af_netlink.c:2309
>> __netlink_dump_start+0x716/0xd60 net/netlink/af_netlink.c:2424
>> netlink_dump_start include/linux/netlink.h:340 [inline]
>> rtnetlink_dump_start net/core/rtnetlink.c:6853 [inline]
>> rtnetlink_rcv_msg+0x1262/0x14b0 net/core/rtnetlink.c:6920
>> netlink_rcv_skb+0x54a/0x680 net/netlink/af_netlink.c:2534
>> rtnetlink_rcv+0x35/0x40 net/core/rtnetlink.c:6982
>> netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
>> netlink_unicast+0xed5/0x1290 net/netlink/af_netlink.c:1339
>> netlink_sendmsg+0x10b3/0x1250 net/netlink/af_netlink.c:1883
>> sock_sendmsg_nosec net/socket.c:712 [inline]
>> __sock_sendmsg+0x330/0x3d0 net/socket.c:727
>> __sys_sendto+0x590/0x710 net/socket.c:2180
>> __do_sys_sendto net/socket.c:2187 [inline]
>> __se_sys_sendto net/socket.c:2183 [inline]
>> __x64_sys_sendto+0x130/0x200 net/socket.c:2183
>> x64_sys_call+0x3c0b/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:45
>> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>> do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
>> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> Uninit was created at:
>> slab_free_hook mm/slub.c:2324 [inline]
>> slab_free mm/slub.c:4656 [inline]
>> kmem_cache_free+0x286/0xf00 mm/slub.c:4758
>> skb_kfree_head net/core/skbuff.c:1056 [inline]
>> skb_free_head net/core/skbuff.c:1070 [inline]
>> skb_release_data+0xe56/0x1110 net/core/skbuff.c:1097
>> skb_release_all net/core/skbuff.c:1162 [inline]
>> __kfree_skb+0x6b/0x260 net/core/skbuff.c:1176
>> consume_skb+0x83/0x230 net/core/skbuff.c:1408
>> netlink_broadcast_filtered+0x21b6/0x2370 net/netlink/af_netlink.c:1524
>> nlmsg_multicast_filtered include/net/netlink.h:1129 [inline]
>> nlmsg_multicast include/net/netlink.h:1148 [inline]
>> nlmsg_notify+0x15b/0x2f0 net/netlink/af_netlink.c:2577
>> rtnl_notify+0xba/0x100 net/core/rtnetlink.c:958
>> inet6_rt_notify+0x27d/0x4a0 net/ipv6/route.c:6270
>> fib6_add_rt2node net/ipv6/ip6_fib.c:1259 [inline]
>> fib6_add+0x33c7/0x6c70 net/ipv6/ip6_fib.c:1488
>> __ip6_ins_rt net/ipv6/route.c:1351 [inline]
>> ip6_ins_rt+0xc0/0x170 net/ipv6/route.c:1361
>> __ipv6_ifa_notify+0x851/0x1990 net/ipv6/addrconf.c:6283
>> ipv6_ifa_notify net/ipv6/addrconf.c:6322 [inline]
>> add_addr+0x301/0x4c0 net/ipv6/addrconf.c:3206
>> init_loopback net/ipv6/addrconf.c:3289 [inline]
>> addrconf_init_auto_addrs+0xb53/0x10e0 net/ipv6/addrconf.c:3564
>> addrconf_notify+0x1643/0x1d10 net/ipv6/addrconf.c:3741
>> notifier_call_chain kernel/notifier.c:85 [inline]
>> raw_notifier_call_chain+0xdd/0x410 kernel/notifier.c:453
>> call_netdevice_notifiers_info+0x1ac/0x2b0 net/core/dev.c:2176
>> call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
>> call_netdevice_notifiers net/core/dev.c:2228 [inline]
>> __dev_notify_flags+0x20d/0x3c0 net/core/dev.c:-1
>> netif_change_flags+0x162/0x1e0 net/core/dev.c:9434
>> dev_change_flags+0x18c/0x320 net/core/dev_api.c:68
>> devinet_ioctl+0x1186/0x2500 net/ipv4/devinet.c:1200
>> inet_ioctl+0x4c0/0x6f0 net/ipv4/af_inet.c:1001
>> sock_do_ioctl+0x9c/0x480 net/socket.c:1190
>> sock_ioctl+0x70b/0xd60 net/socket.c:1311
>> vfs_ioctl fs/ioctl.c:51 [inline]
>> __do_sys_ioctl fs/ioctl.c:906 [inline]
>> __se_sys_ioctl+0x239/0x400 fs/ioctl.c:892
>> __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:892
>> x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
>> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>> do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
>> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> CPU: 1 UID: 0 PID: 5440 Comm: dhcpcd Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(undef)
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
>> =====================================================
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>>
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>>
>> If you want to undo deduplication, reply with:
>> #syz undup
>