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Date: Sat, 06 Apr 2024 04:00:23 -0700
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Subject: Re: [syzbot] [nilfs?] KMSAN: uninit-value in nilfs_add_checksums_on_logs
 (2)
From: syzbot <syzbot+47a017c46edb25eff048@syzkaller.appspotmail.com>
To: konishi.ryusuke@gmail.com, linux-fsdevel@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-nilfs@vger.kernel.org, 
	syzkaller-bugs@googlegroups.com, xrivendell7@gmail.com
Content-Type: text/plain; charset="UTF-8"

syzbot has found a reproducer for the following issue on:

HEAD commit:    e8b0ccb2a787 Merge tag '9p-for-6.9-rc3' of https://github...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=115eb623180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5112b3f484393436
dashboard link: https://syzkaller.appspot.com/bug?extid=47a017c46edb25eff048
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=156679a1180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f27ef6180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cf4b0d1e3b2d/disk-e8b0ccb2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/422cac6cc940/vmlinux-e8b0ccb2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9a4df48e199b/bzImage-e8b0ccb2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/69e1e69e7522/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47a017c46edb25eff048@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in crc32_body lib/crc32.c:110 [inline]
BUG: KMSAN: uninit-value in crc32_le_generic lib/crc32.c:179 [inline]
BUG: KMSAN: uninit-value in crc32_le_base+0x43c/0xd80 lib/crc32.c:197
 crc32_body lib/crc32.c:110 [inline]
 crc32_le_generic lib/crc32.c:179 [inline]
 crc32_le_base+0x43c/0xd80 lib/crc32.c:197
 nilfs_segbuf_fill_in_data_crc fs/nilfs2/segbuf.c:224 [inline]
 nilfs_add_checksums_on_logs+0xb80/0xe40 fs/nilfs2/segbuf.c:327
 nilfs_segctor_do_construct+0x9876/0xdeb0 fs/nilfs2/segment.c:2078
 nilfs_segctor_construct+0x1eb/0xe30 fs/nilfs2/segment.c:2381
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2489 [inline]
 nilfs_segctor_thread+0xc50/0x11e0 fs/nilfs2/segment.c:2573
 kthread+0x3e2/0x540 kernel/kthread.c:388
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

Uninit was stored to memory at:
 memcpy_from_iter lib/iov_iter.c:73 [inline]
 iterate_bvec include/linux/iov_iter.h:122 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:249 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 copy_page_from_iter_atomic+0x12b7/0x2b60 lib/iov_iter.c:481
 generic_perform_write+0x4c1/0xc60 mm/filemap.c:3982
 __generic_file_write_iter+0x20a/0x460 mm/filemap.c:4069
 generic_file_write_iter+0x103/0x5b0 mm/filemap.c:4095
 __kernel_write_iter+0x68b/0xc40 fs/read_write.c:523
 dump_emit_page fs/coredump.c:890 [inline]
 dump_user_range+0x8dc/0xee0 fs/coredump.c:951
 elf_core_dump+0x520f/0x59c0 fs/binfmt_elf.c:2077
 do_coredump+0x32d5/0x4920 fs/coredump.c:764
 get_signal+0x267e/0x2d00 kernel/signal.c:2896
 arch_do_signal_or_restart+0x53/0xcb0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x5d/0x160 kernel/entry/common.c:218
 do_syscall_64+0xe4/0x1f0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

Uninit was created at:
 __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
 alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264
 alloc_pages+0x1bf/0x1e0 mm/mempolicy.c:2335
 dump_user_range+0x4a/0xee0 fs/coredump.c:935
 elf_core_dump+0x520f/0x59c0 fs/binfmt_elf.c:2077
 do_coredump+0x32d5/0x4920 fs/coredump.c:764
 get_signal+0x267e/0x2d00 kernel/signal.c:2896
 arch_do_signal_or_restart+0x53/0xcb0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x5d/0x160 kernel/entry/common.c:218
 do_syscall_64+0xe4/0x1f0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

CPU: 0 PID: 5014 Comm: segctord Not tainted 6.9.0-rc2-syzkaller-00207-ge8b0ccb2a787 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


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