[syzbot] [serial?] KMSAN: kernel-infoleak in con_font_op (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8f602276d390 Merge tag 'bcachefs-2024-10-05' of git://evil..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a8f307980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d302f14701986aa0
dashboard link: https://syzkaller.appspot.com/bug?extid=955da2d57931604ee691
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/241996bfa3de/disk-8f602276.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/417de1b4ca32/vmlinux-8f602276.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2c793c19b953/bzImage-8f602276.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+955da2d57931604ee691@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in _inline_copy_to_user include/linux/uaccess.h:187 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x110 lib/usercopy.c:26
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 _inline_copy_to_user include/linux/uaccess.h:187 [inline]
 _copy_to_user+0xbc/0x110 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:216 [inline]
 con_font_get drivers/tty/vt/vt.c:4760 [inline]
 con_font_op+0x14a2/0x1710 drivers/tty/vt/vt.c:4854
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x2b6e/0x2fe0 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0xd0c/0x1990 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x25e/0x450 fs/ioctl.c:893
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:893
 x64_sys_call+0x18bf/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 ___kmalloc_large_node+0x22c/0x370 mm/slub.c:4219
 __kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4236
 __do_kmalloc_node mm/slub.c:4252 [inline]
 __kmalloc_node_noprof+0x9d6/0xf50 mm/slub.c:4270
 __kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:658
 con_font_get drivers/tty/vt/vt.c:4729 [inline]
 con_font_op+0x659/0x1710 drivers/tty/vt/vt.c:4854
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x2b6e/0x2fe0 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0xd0c/0x1990 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x25e/0x450 fs/ioctl.c:893
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:893
 x64_sys_call+0x18bf/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Bytes 61440-76799 of 76800 are uninitialized
Memory access of size 76800 starts at ffff8880b5c00000
Data copied to user address 0000000020000880

CPU: 0 UID: 0 PID: 7973 Comm: syz.2.4245 Tainted: G        W          6.12.0-rc1-syzkaller-00349-g8f602276d390 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
=====================================================


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