[syzbot] [i2c?] KMSAN: uninit-value in __i2c_smbus_xfer

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 02ddfb981de8 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1034139b980000
kernel config: https://syzkaller.appspot.com/x/.config?x=9dc42c34a3f5c357
dashboard link: https://syzkaller.appspot.com/bug?extid=0a36c1fec090c67a9885
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10c9df74580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1550f1b3980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ca57f5a3f77/disk-02ddfb98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3f23cbc11e68/vmlinux-02ddfb98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73e63afac354/bzImage-02ddfb98.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a36c1...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:481 [inline]
BUG: KMSAN: uninit-value in __i2c_smbus_xfer+0x23e7/0x2f60 drivers/i2c/i2c-core-smbus.c:607
i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:481 [inline]
__i2c_smbus_xfer+0x23e7/0x2f60 drivers/i2c/i2c-core-smbus.c:607
i2c_smbus_xfer+0x31d/0x4d0 drivers/i2c/i2c-core-smbus.c:545
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: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

Local variable page created at:
get_futex_key+0x6f/0x11d0 kernel/futex/core.c:227
futex_wake+0xfe/0x890 kernel/futex/waitwake.c:166

CPU: 1 UID: 0 PID: 5795 Comm: syz-executor470 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
=====================================================


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