Re: [syzbot] [crypto?] KMSAN: uninit-value in adiantum_crypt

[Eric Biggers <ebiggers@kernel.org>]

On Tue, Dec 02, 2025 at 05:57:26PM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    6cf62f0174de Merge tag 'char-misc-6.18-rc8' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1727df42580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=61a9bf3cc5d17a01
> dashboard link: https://syzkaller.appspot.com/bug?extid=703d8a2cd20971854b06
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13bfa112580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=169e422c580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/fb216361ff9c/disk-6cf62f01.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/eb55e25eb970/vmlinux-6cf62f01.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/5110f00a1a4e/bzImage-6cf62f01.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/7a62729c5268/mount_0.gz
>   fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=16dd8112580000)
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+703d8a2cd20971854b06@syzkaller.appspotmail.com
> 
> =====================================================
> 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
>  cipher_crypt_one+0x120/0x2e0 crypto/cipher.c:75
>  crypto_cipher_encrypt_one+0x33/0x40 crypto/cipher.c:82
>  adiantum_crypt+0x939/0xe60 crypto/adiantum.c:383
>  adiantum_encrypt+0x33/0x40 crypto/adiantum.c:419
>  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 sometimes encrypts uninitialized memory.  Duplicate of already-
reported bug, see https://lore.kernel.org/r/20251210022202.GB4128@sol/

#syz dup: KMSAN: uninit-value in fscrypt_crypt_data_unit

- Eric