linux-kernel - Re: [syzbot] [i2c?] KMSAN: uninit-value in __i2c_smbus

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Message-ID: <683824e3.a00a0220.52848.0001.GAE@google.com>
Date: Thu, 29 May 2025 02:12:03 -0700
From: syzbot <syzbot+0a36c1fec090c67a9885@...kaller.appspotmail.com>
To: abhinav.ogl@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [i2c?] KMSAN: uninit-value in __i2c_smbus_xfer

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in __i2c_smbus_xfer

=====================================================
BUG: KMSAN: uninit-value in i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:484 [inline]
BUG: KMSAN: uninit-value in __i2c_smbus_xfer+0x2542/0x3140 drivers/i2c/i2c-core-smbus.c:610
 i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:484 [inline]
 __i2c_smbus_xfer+0x2542/0x3140 drivers/i2c/i2c-core-smbus.c:610
 i2c_smbus_xfer+0x31d/0x4d0 drivers/i2c/i2c-core-smbus.c:548
 i2cdev_ioctl_smbus+0x4a1/0x660 drivers/i2c/i2c-dev.c:389
 i2cdev_ioctl+0xa14/0xf40 drivers/i2c/i2c-dev.c:478
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x239/0x400 fs/ioctl.c:893
 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:893
 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+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable msgbuf0.i created at:
 i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:335 [inline]
 __i2c_smbus_xfer+0x864/0x3140 drivers/i2c/i2c-core-smbus.c:610
 i2c_smbus_xfer+0x31d/0x4d0 drivers/i2c/i2c-core-smbus.c:548

CPU: 0 UID: 0 PID: 7066 Comm: syz.0.33 Not tainted 6.15.0-syzkaller-07774-g90b83efa6701-dirty #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
=====================================================


Tested on:

commit:         90b83efa Merge tag 'bpf-next-6.16' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13654970580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1da44e3e5e6013db
dashboard link: https://syzkaller.appspot.com/bug?extid=0a36c1fec090c67a9885
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12534ed4580000