netdev - [syzbot] [tipc?] KMSAN: uninit-value in tipc

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Message-ID: <6880f58e.050a0220.248954.0001.GAE@google.com>
Date: Wed, 23 Jul 2025 07:45:34 -0700
From: syzbot <syzbot+9a4fbb77c9d4aacd3388@...kaller.appspotmail.com>
To: davem@...emloft.net, edumazet@...gle.com, horms@...nel.org, 
	jmaloy@...hat.com, kuba@...nel.org, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com, 
	tipc-discussion@...ts.sourceforge.net
Subject: [syzbot] [tipc?] KMSAN: uninit-value in tipc_rcv (2)

Hello,

syzbot found the following issue on:

HEAD commit:    4871b7cb27f4 Merge tag 'v6.16-rc6-smb3-client-fixes' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15bbe38c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5227c65742122bdd
dashboard link: https://syzkaller.appspot.com/bug?extid=9a4fbb77c9d4aacd3388
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e2e34a7999ba/disk-4871b7cb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/834fdc8dbc07/vmlinux-4871b7cb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/617fadfb9a8e/bzImage-4871b7cb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9a4fbb77c9d4aacd3388@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in tipc_rcv+0x17fa/0x1ea0 net/tipc/node.c:2132
 tipc_rcv+0x17fa/0x1ea0 net/tipc/node.c:2132
 tipc_l2_rcv_msg+0x213/0x320 net/tipc/bearer.c:668
 __netif_receive_skb_list_ptype net/core/dev.c:6025 [inline]
 __netif_receive_skb_list_core+0x133b/0x16b0 net/core/dev.c:6067
 __netif_receive_skb_list net/core/dev.c:6119 [inline]
 netif_receive_skb_list_internal+0xee7/0x1530 net/core/dev.c:6210
 gro_normal_list include/net/gro.h:532 [inline]
 napi_complete_done+0x3fb/0x7d0 net/core/dev.c:6580
 napi_complete include/linux/netdevice.h:588 [inline]
 tun_get_user+0x4ac4/0x6b40 drivers/net/tun.c:1909
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 do_iter_readv_writev+0x94a/0xba0 fs/read_write.c:-1
 vfs_writev+0x52a/0x1500 fs/read_write.c:1057
 do_writev+0x1b5/0x580 fs/read_write.c:1103
 __do_sys_writev fs/read_write.c:1171 [inline]
 __se_sys_writev fs/read_write.c:1168 [inline]
 __ia32_sys_writev+0x9c/0xf0 fs/read_write.c:1168
 ia32_sys_call+0x3f2a/0x42c0 arch/x86/include/generated/asm/syscalls_32.h:147
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 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:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4249
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579
 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670
 napi_alloc_skb+0xc1/0x740 net/core/skbuff.c:812
 napi_get_frags+0xab/0x250 net/core/gro.c:673
 tun_napi_alloc_frags drivers/net/tun.c:1404 [inline]
 tun_get_user+0x1246/0x6b40 drivers/net/tun.c:1772
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 do_iter_readv_writev+0x94a/0xba0 fs/read_write.c:-1
 vfs_writev+0x52a/0x1500 fs/read_write.c:1057
 do_writev+0x1b5/0x580 fs/read_write.c:1103
 __do_sys_writev fs/read_write.c:1171 [inline]
 __se_sys_writev fs/read_write.c:1168 [inline]
 __ia32_sys_writev+0x9c/0xf0 fs/read_write.c:1168
 ia32_sys_call+0x3f2a/0x42c0 arch/x86/include/generated/asm/syscalls_32.h:147
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 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: 15202 Comm: syz.3.3410 Not tainted 6.16.0-rc6-syzkaller-00253-g4871b7cb27f4 #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
=====================================================


---
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