[syzbot] [media?] KMSAN: uninit-value in pctv452e_i2c_msg

[syzbot <syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    9b0d551bcc05 Merge tag 'pull-misc' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14e89a7c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=50fb29d81ff5a3df
dashboard link: https://syzkaller.appspot.com/bug?extid=480edd2cadb85ddb4bbe
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/90b0fb888152/disk-9b0d551b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1120c646f284/vmlinux-9b0d551b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/df9bbfa8cbe6/bzImage-9b0d551b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in hex_string+0x681/0x740 lib/vsprintf.c:1220
 hex_string+0x681/0x740 lib/vsprintf.c:1220
 pointer+0x2c7/0x1bd0 lib/vsprintf.c:2520
 vsnprintf+0xf8a/0x1bd0 lib/vsprintf.c:2930
 vscnprintf+0x6d/0x120 lib/vsprintf.c:2991
 printk_sprint+0x53/0x5c0 kernel/printk/printk.c:2189
 vprintk_store+0xbb9/0x1530 kernel/printk/printk.c:2309
 vprintk_emit+0x21a/0xb60 kernel/printk/printk.c:2399
 vprintk_default+0x3f/0x50 kernel/printk/printk.c:2438
 vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
 _printk+0x17e/0x1b0 kernel/printk/printk.c:2448
 pctv452e_i2c_msg+0x82a/0x8f0 drivers/media/usb/dvb-usb/pctv452e.c:467
 pctv452e_i2c_xfer+0x2e6/0x4c0 drivers/media/usb/dvb-usb/pctv452e.c:502
 __i2c_transfer+0xecd/0x3110 drivers/i2c/i2c-core-base.c:-1
 i2c_transfer+0x300/0x4b0 drivers/i2c/i2c-core-base.c:2317
 i2c_transfer_buffer_flags+0x138/0x200 drivers/i2c/i2c-core-base.c:2345
 i2c_master_recv include/linux/i2c.h:79 [inline]
 i2cdev_read+0x1b2/0x3c0 drivers/i2c/i2c-dev.c:155
 vfs_read+0x27c/0xf90 fs/read_write.c:570
 ksys_pread64 fs/read_write.c:763 [inline]
 __do_sys_pread64 fs/read_write.c:771 [inline]
 __se_sys_pread64 fs/read_write.c:768 [inline]
 __x64_sys_pread64+0x2ab/0x3b0 fs/read_write.c:768
 x64_sys_call+0x3370/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:18
 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

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5245 [inline]
 __kmalloc_cache_noprof+0x8f5/0x16b0 mm/slub.c:5719
 kmalloc_noprof include/linux/slab.h:957 [inline]
 pctv452e_i2c_msg+0x98/0x8f0 drivers/media/usb/dvb-usb/pctv452e.c:425
 pctv452e_i2c_xfer+0x2e6/0x4c0 drivers/media/usb/dvb-usb/pctv452e.c:502
 __i2c_transfer+0xecd/0x3110 drivers/i2c/i2c-core-base.c:-1
 i2c_transfer+0x300/0x4b0 drivers/i2c/i2c-core-base.c:2317
 i2c_transfer_buffer_flags+0x138/0x200 drivers/i2c/i2c-core-base.c:2345
 i2c_master_recv include/linux/i2c.h:79 [inline]
 i2cdev_read+0x1b2/0x3c0 drivers/i2c/i2c-dev.c:155
 vfs_read+0x27c/0xf90 fs/read_write.c:570
 ksys_pread64 fs/read_write.c:763 [inline]
 __do_sys_pread64 fs/read_write.c:771 [inline]
 __se_sys_pread64 fs/read_write.c:768 [inline]
 __x64_sys_pread64+0x2ab/0x3b0 fs/read_write.c:768
 x64_sys_call+0x3370/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:18
 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

CPU: 1 UID: 0 PID: 10013 Comm: syz.1.697 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
=====================================================


---
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@googlegroups.com.

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