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Subject[syzbot] KMSAN: uninit-value in pagecache_write
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Hello,

syzbot found the following issue on:

HEAD commit: 968c2729e576 x86: kmsan: fix comment in kmsan_shadow.c
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=11d01ad6880000
kernel config: https://syzkaller.appspot.com/x/.config?x=131312b26465c190
dashboard link: https://syzkaller.appspot.com/bug?extid=9767be679ef5016b6082
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project.git 610139d2d9ce6746b3c617fb3e2f7886272d26ff), GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c78ce21b953f/disk-968c2729.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/22868d826804/vmlinux-968c2729.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9767be679ef5016b6082@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in pagecache_write+0x655/0x720 fs/ext4/verity.c:91
pagecache_write+0x655/0x720 fs/ext4/verity.c:91
ext4_write_merkle_tree_block+0x84/0xa0 fs/ext4/verity.c:389
build_merkle_tree_level+0x972/0x1250 fs/verity/enable.c:121
build_merkle_tree fs/verity/enable.c:182 [inline]
enable_verity+0xede/0x1920 fs/verity/enable.c:268
fsverity_ioctl_enable+0x895/0xab0 fs/verity/enable.c:392
__ext4_ioctl fs/ext4/ioctl.c:1572 [inline]
ext4_ioctl+0x26dd/0x8c50 fs/ext4/ioctl.c:1606
ext4_compat_ioctl+0x702/0x800 fs/ext4/ioctl.c:1682
__do_compat_sys_ioctl fs/ioctl.c:968 [inline]
__se_compat_sys_ioctl+0x781/0xfa0 fs/ioctl.c:910
__ia32_compat_sys_ioctl+0x8f/0xd0 fs/ioctl.c:910
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82

Local variable fsdata created at:
pagecache_write+0x21c/0x720 fs/ext4/verity.c:85
ext4_write_merkle_tree_block+0x84/0xa0 fs/ext4/verity.c:389

CPU: 1 PID: 15121 Comm: syz-executor.3 Not tainted 6.0.0-rc5-syzkaller-48543-g968c2729e576 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
=====================================================


---
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.

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