linux-kernel - Re: [syzbot] [crypto?] KMSAN: uninit-value in fscrypt_crypt_data

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Message-ID: <CANp29Y6VadSqY3Pt8Leih+W+czo7-yYZE33juiaCKLHYZQ1p4w@mail.gmail.com>
Date: Tue, 14 Oct 2025 16:58:54 +0200
From: Aleksandr Nogikh <nogikh@...gle.com>
To: syzbot <syzbot+7add5c56bc2a14145d20@...kaller.appspotmail.com>
Cc: davem@...emloft.net, herbert@...dor.apana.org.au, 
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, linux-ext4@...r.kernel.org, 
	linux-fscrypt@...r.kernel.org, Eric Biggers <ebiggers@...nel.org>
Subject: Re: [syzbot] [crypto?] KMSAN: uninit-value in fscrypt_crypt_data_unit

#syz set subsystems: ext4, fscrypt

On Tue, Oct 14, 2025 at 4:50 PM syzbot
<syzbot+7add5c56bc2a14145d20@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    3a8660878839 Linux 6.18-rc1
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13d25dcd980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=bbd3e7f3c2e28265
> dashboard link: https://syzkaller.appspot.com/bug?extid=7add5c56bc2a14145d20
> 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/d996feb56093/disk-3a866087.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/fa6f6bc3b02a/vmlinux-3a866087.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/7571083a68d6/bzImage-3a866087.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+7add5c56bc2a14145d20@...kaller.appspotmail.com
>
> EXT4-fs (loop5): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
> =====================================================
> BUG: KMSAN: uninit-value in subshift lib/crypto/aes.c:150 [inline]
> BUG: KMSAN: uninit-value in aes_encrypt+0x1239/0x1960 lib/crypto/aes.c:283
>  subshift lib/crypto/aes.c:150 [inline]
>  aes_encrypt+0x1239/0x1960 lib/crypto/aes.c:283
>  aesti_encrypt+0x7d/0xf0 crypto/aes_ti.c:31
>  crypto_ecb_crypt crypto/ecb.c:23 [inline]
>  crypto_ecb_encrypt2+0x142/0x300 crypto/ecb.c:40
>  crypto_lskcipher_crypt_sg+0x3ac/0x930 crypto/lskcipher.c:188
>  crypto_lskcipher_encrypt_sg+0x8b/0xc0 crypto/lskcipher.c:207
>  crypto_skcipher_encrypt+0x111/0x1e0 crypto/skcipher.c:194
>  xts_encrypt+0x2e1/0x570 crypto/xts.c:269
>  crypto_skcipher_encrypt+0x18a/0x1e0 crypto/skcipher.c:195
>  fscrypt_crypt_data_unit+0x38e/0x590 fs/crypto/crypto.c:139
>  fscrypt_encrypt_pagecache_blocks+0x430/0x900 fs/crypto/crypto.c:197
>  ext4_bio_write_folio+0x1383/0x30d0 fs/ext4/page-io.c:552
>  mpage_submit_folio fs/ext4/inode.c:2080 [inline]
>  mpage_process_page_bufs+0xf1b/0x13e0 fs/ext4/inode.c:2191
>  mpage_prepare_extent_to_map+0x1792/0x2a10 fs/ext4/inode.c:2736
>  ext4_do_writepages+0x11b6/0x8020 fs/ext4/inode.c:2877
>  ext4_writepages+0x338/0x870 fs/ext4/inode.c:3025
>  do_writepages+0x3f2/0x860 mm/page-writeback.c:2604
>  filemap_fdatawrite_wbc mm/filemap.c:389 [inline]
>  __filemap_fdatawrite_range mm/filemap.c:422 [inline]
>  file_write_and_wait_range+0x6f0/0x7d0 mm/filemap.c:797
>  generic_buffers_fsync_noflush+0x79/0x3c0 fs/buffer.c:609
>  ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
>  ext4_sync_file+0x587/0x12f0 fs/ext4/fsync.c:147
>  vfs_fsync_range+0x1a1/0x240 fs/sync.c:187
>  generic_write_sync include/linux/fs.h:3046 [inline]
>  ext4_buffered_write_iter+0xae9/0xce0 fs/ext4/file.c:305
>  ext4_file_write_iter+0x2a2/0x3d90 fs/ext4/file.c:-1
>  new_sync_write fs/read_write.c:593 [inline]
>  vfs_write+0xbe2/0x15d0 fs/read_write.c:686
>  ksys_pwrite64 fs/read_write.c:793 [inline]
>  __do_sys_pwrite64 fs/read_write.c:801 [inline]
>  __se_sys_pwrite64 fs/read_write.c:798 [inline]
>  __x64_sys_pwrite64+0x2ab/0x3b0 fs/read_write.c:798
>  x64_sys_call+0xe77/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:19
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Uninit was stored to memory at:
>  le128_xor include/crypto/b128ops.h:69 [inline]
>  xts_xor_tweak+0x566/0xbd0 crypto/xts.c:123
>  xts_xor_tweak_pre crypto/xts.c:135 [inline]
>  xts_encrypt+0x278/0x570 crypto/xts.c:268
>  crypto_skcipher_encrypt+0x18a/0x1e0 crypto/skcipher.c:195
>  fscrypt_crypt_data_unit+0x38e/0x590 fs/crypto/crypto.c:139
>  fscrypt_encrypt_pagecache_blocks+0x430/0x900 fs/crypto/crypto.c:197
>  ext4_bio_write_folio+0x1383/0x30d0 fs/ext4/page-io.c:552
>  mpage_submit_folio fs/ext4/inode.c:2080 [inline]
>  mpage_process_page_bufs+0xf1b/0x13e0 fs/ext4/inode.c:2191
>  mpage_prepare_extent_to_map+0x1792/0x2a10 fs/ext4/inode.c:2736
>  ext4_do_writepages+0x11b6/0x8020 fs/ext4/inode.c:2877
>  ext4_writepages+0x338/0x870 fs/ext4/inode.c:3025
>  do_writepages+0x3f2/0x860 mm/page-writeback.c:2604
>  filemap_fdatawrite_wbc mm/filemap.c:389 [inline]
>  __filemap_fdatawrite_range mm/filemap.c:422 [inline]
>  file_write_and_wait_range+0x6f0/0x7d0 mm/filemap.c:797
>  generic_buffers_fsync_noflush+0x79/0x3c0 fs/buffer.c:609
>  ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
>  ext4_sync_file+0x587/0x12f0 fs/ext4/fsync.c:147
>  vfs_fsync_range+0x1a1/0x240 fs/sync.c:187
>  generic_write_sync include/linux/fs.h:3046 [inline]
>  ext4_buffered_write_iter+0xae9/0xce0 fs/ext4/file.c:305
>  ext4_file_write_iter+0x2a2/0x3d90 fs/ext4/file.c:-1
>  new_sync_write fs/read_write.c:593 [inline]
>  vfs_write+0xbe2/0x15d0 fs/read_write.c:686
>  ksys_pwrite64 fs/read_write.c:793 [inline]
>  __do_sys_pwrite64 fs/read_write.c:801 [inline]
>  __se_sys_pwrite64 fs/read_write.c:798 [inline]
>  __x64_sys_pwrite64+0x2ab/0x3b0 fs/read_write.c:798
>  x64_sys_call+0xe77/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:19
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Uninit was created at:
>  __alloc_frozen_pages_noprof+0x689/0xf00 mm/page_alloc.c:5206
>  alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2416
>  alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
>  alloc_pages_noprof mm/mempolicy.c:2507 [inline]
>  folio_alloc_noprof+0x109/0x360 mm/mempolicy.c:2517
>  filemap_alloc_folio_noprof+0x9d/0x420 mm/filemap.c:1020
>  __filemap_get_folio+0xb45/0x1930 mm/filemap.c:2012
>  write_begin_get_folio include/linux/pagemap.h:784 [inline]
>  ext4_write_begin+0x6d9/0x2d70 fs/ext4/inode.c:1318
>  generic_perform_write+0x365/0x1050 mm/filemap.c:4242
>  ext4_buffered_write_iter+0x61a/0xce0 fs/ext4/file.c:299
>  ext4_file_write_iter+0x2a2/0x3d90 fs/ext4/file.c:-1
>  new_sync_write fs/read_write.c:593 [inline]
>  vfs_write+0xbe2/0x15d0 fs/read_write.c:686
>  ksys_pwrite64 fs/read_write.c:793 [inline]
>  __do_sys_pwrite64 fs/read_write.c:801 [inline]
>  __se_sys_pwrite64 fs/read_write.c:798 [inline]
>  __x64_sys_pwrite64+0x2ab/0x3b0 fs/read_write.c:798
>  x64_sys_call+0xe77/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:19
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> CPU: 1 UID: 0 PID: 5879 Comm: syz.5.3882 Tainted: G        W           syzkaller #0 PREEMPT(none)
> Tainted: [W]=WARN
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
> =====================================================
>
>
> ---
> 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@...glegroups.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
>
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