syzbot


KMSAN: uninit-value in do_output_route4

Status: upstream: reported on 2025/05/01 15:06
Subsystems: lvs
[Documentation on labels]
Reported-by: syzbot+04b9a82855c8aed20860@syzkaller.appspotmail.com
First crash: 35d, last: 9d15h
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] [lvs?] KMSAN: uninit-value in do_output_route4 1 (2) 2025/05/02 22:15
[PATCH nf] ipvs: fix uninit-value for saddr in do_output_route4 1 (1) 2025/05/02 22:01

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in do_output_route4+0x42c/0x4d0 net/netfilter/ipvs/ip_vs_xmit.c:147
 do_output_route4+0x42c/0x4d0 net/netfilter/ipvs/ip_vs_xmit.c:147
 __ip_vs_get_out_rt+0x403/0x21d0 net/netfilter/ipvs/ip_vs_xmit.c:330
 ip_vs_tunnel_xmit+0x205/0x2380 net/netfilter/ipvs/ip_vs_xmit.c:1136
 ip_vs_in_hook+0x1aa5/0x35b0 net/netfilter/ipvs/ip_vs_core.c:2063
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf7/0x400 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:269 [inline]
 __ip_local_out+0x758/0x7e0 net/ipv4/ip_output.c:118
 ip_local_out net/ipv4/ip_output.c:127 [inline]
 ip_send_skb+0x6a/0x3c0 net/ipv4/ip_output.c:1501
 udp_send_skb+0xfda/0x1b70 net/ipv4/udp.c:1195
 udp_sendmsg+0x2fe3/0x33c0 net/ipv4/udp.c:1483
 inet_sendmsg+0x1fc/0x280 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x267/0x380 net/socket.c:727
 ____sys_sendmsg+0x91b/0xda0 net/socket.c:2566
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2620
 __sys_sendmmsg+0x41d/0x880 net/socket.c:2702
 __compat_sys_sendmmsg net/compat.c:360 [inline]
 __do_compat_sys_sendmmsg net/compat.c:367 [inline]
 __se_compat_sys_sendmmsg net/compat.c:364 [inline]
 __ia32_compat_sys_sendmmsg+0xc8/0x140 net/compat.c:364
 ia32_sys_call+0x3ffa/0x41f0 arch/x86/include/generated/asm/syscalls_32.h:346
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4167 [inline]
 slab_alloc_node mm/slub.c:4210 [inline]
 __kmalloc_cache_noprof+0x8fa/0xe00 mm/slub.c:4367
 kmalloc_noprof include/linux/slab.h:905 [inline]
 ip_vs_dest_dst_alloc net/netfilter/ipvs/ip_vs_xmit.c:61 [inline]
 __ip_vs_get_out_rt+0x35d/0x21d0 net/netfilter/ipvs/ip_vs_xmit.c:323
 ip_vs_tunnel_xmit+0x205/0x2380 net/netfilter/ipvs/ip_vs_xmit.c:1136
 ip_vs_in_hook+0x1aa5/0x35b0 net/netfilter/ipvs/ip_vs_core.c:2063
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf7/0x400 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:269 [inline]
 __ip_local_out+0x758/0x7e0 net/ipv4/ip_output.c:118
 ip_local_out net/ipv4/ip_output.c:127 [inline]
 ip_send_skb+0x6a/0x3c0 net/ipv4/ip_output.c:1501
 udp_send_skb+0xfda/0x1b70 net/ipv4/udp.c:1195
 udp_sendmsg+0x2fe3/0x33c0 net/ipv4/udp.c:1483
 inet_sendmsg+0x1fc/0x280 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x267/0x380 net/socket.c:727
 ____sys_sendmsg+0x91b/0xda0 net/socket.c:2566
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2620
 __sys_sendmmsg+0x41d/0x880 net/socket.c:2702
 __compat_sys_sendmmsg net/compat.c:360 [inline]
 __do_compat_sys_sendmmsg net/compat.c:367 [inline]
 __se_compat_sys_sendmmsg net/compat.c:364 [inline]
 __ia32_compat_sys_sendmmsg+0xc8/0x140 net/compat.c:364
 ia32_sys_call+0x3ffa/0x41f0 arch/x86/include/generated/asm/syscalls_32.h:346
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 0 UID: 0 PID: 22408 Comm: syz.4.5165 Not tainted 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
=====================================================

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/23 21:46 upstream bc3372351d0c d971f7e2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/11 18:04 upstream 900241a5cc15 12ba9c21 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/11 18:04 upstream 900241a5cc15 12ba9c21 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/01 23:07 upstream 08733088b566 d863cf4b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/01 23:07 upstream 08733088b566 d863cf4b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/01 23:04 upstream 08733088b566 d863cf4b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/04/01 23:04 upstream 08733088b566 d863cf4b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
2025/03/29 06:59 upstream eff5f16bfd87 cf25e2c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in do_output_route4
* Struck through repros no longer work on HEAD.