linux-kernel - Re: [syzbot] [ext4] [fscrypt] KMSAN: uninit-value in fscrypt_crypt_data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <69380321.050a0220.1ff09b.0000.GAE@google.com>
Date: Tue, 09 Dec 2025 03:08:17 -0800
From: syzbot <syzbot+7add5c56bc2a14145d20@...kaller.appspotmail.com>
To: davem@...emloft.net, ebiggers@...nel.org, herbert@...dor.apana.org.au, 
	jaegeuk@...nel.org, linux-crypto@...r.kernel.org, linux-ext4@...r.kernel.org, 
	linux-fscrypt@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: Re: [syzbot] [ext4] [fscrypt] KMSAN: uninit-value in fscrypt_crypt_data_unit

syzbot has found a reproducer for the following issue on:

HEAD commit:    a110f942672c Merge tag 'pinctrl-v6.19-1' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17495992580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=10d58c94af5f9772
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
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1122aec2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14012a1a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/905b868d0b1d/disk-a110f942.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aa7281cd9720/vmlinux-a110f942.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1420de8a7da2/bzImage-a110f942.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1e40f788aa89/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=1622aec2580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7add5c56bc2a14145d20@...kaller.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
 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:443
 xts_encrypt+0x2e1/0x570 crypto/xts.c:269
 crypto_skcipher_encrypt+0x18a/0x1e0 crypto/skcipher.c:444
 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+0x399/0x3d0 fs/ext4/inode.c:2087
 mpage_process_page_bufs+0xaef/0xf50 fs/ext4/inode.c:2198
 mpage_prepare_extent_to_map+0x175d/0x2660 fs/ext4/inode.c:2737
 ext4_do_writepages+0x1aa1/0x77a0 fs/ext4/inode.c:2930
 ext4_writepages+0x338/0x870 fs/ext4/inode.c:3026
 do_writepages+0x3f2/0x860 mm/page-writeback.c:2598
 __writeback_single_inode+0x101/0x1190 fs/fs-writeback.c:1737
 writeback_sb_inodes+0xb2d/0x1f10 fs/fs-writeback.c:2030
 wb_writeback+0x4ce/0xc00 fs/fs-writeback.c:2216
 wb_do_writeback fs/fs-writeback.c:2363 [inline]
 wb_workfn+0x397/0x1910 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3340
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3421
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x208/0x710 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

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:444
 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+0x399/0x3d0 fs/ext4/inode.c:2087
 mpage_process_page_bufs+0xaef/0xf50 fs/ext4/inode.c:2198
 mpage_prepare_extent_to_map+0x175d/0x2660 fs/ext4/inode.c:2737
 ext4_do_writepages+0x1aa1/0x77a0 fs/ext4/inode.c:2930
 ext4_writepages+0x338/0x870 fs/ext4/inode.c:3026
 do_writepages+0x3f2/0x860 mm/page-writeback.c:2598
 __writeback_single_inode+0x101/0x1190 fs/fs-writeback.c:1737
 writeback_sb_inodes+0xb2d/0x1f10 fs/fs-writeback.c:2030
 wb_writeback+0x4ce/0xc00 fs/fs-writeback.c:2216
 wb_do_writeback fs/fs-writeback.c:2363 [inline]
 wb_workfn+0x397/0x1910 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3340
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3421
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x208/0x710 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Uninit was created at:
 __alloc_frozen_pages_noprof+0x421/0xab0 mm/page_alloc.c:5233
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2486
 alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
 alloc_pages_noprof mm/mempolicy.c:2577 [inline]
 folio_alloc_noprof+0x109/0x360 mm/mempolicy.c:2587
 filemap_alloc_folio_noprof+0xda/0x480 mm/filemap.c:1013
 __filemap_get_folio_mpol+0xb4f/0x1960 mm/filemap.c:2006
 __filemap_get_folio include/linux/pagemap.h:763 [inline]
 write_begin_get_folio include/linux/pagemap.h:789 [inline]
 ext4_write_begin+0x6d3/0x2d70 fs/ext4/inode.c:1323
 generic_perform_write+0x365/0x1050 mm/filemap.c:4314
 ext4_buffered_write_iter+0x61a/0xce0 fs/ext4/file.c:299
 ext4_file_write_iter+0x2a2/0x3d90 fs/ext4/file.c:-1
 aio_write+0x704/0xa10 fs/aio.c:1634
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0x260e/0x3450 fs/aio.c:2053
 __do_sys_io_submit fs/aio.c:2112 [inline]
 __se_sys_io_submit+0x27c/0x6a0 fs/aio.c:2082
 __x64_sys_io_submit+0x97/0xe0 fs/aio.c:2082
 x64_sys_call+0x3b5f/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:210
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 1143 Comm: kworker/u8:8 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:0)
=====================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.