linux-kernel - [syzbot] [crypto?] KMSAN: uninit-value in poly1305

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Message-ID: <68f6a48f.050a0220.91a22.0452.GAE@google.com>
Date: Mon, 20 Oct 2025 14:07:27 -0700
From: syzbot <syzbot+01fcd39a0d90cdb0e3df@...kaller.appspotmail.com>
To: davem@...emloft.net, herbert@...dor.apana.org.au, 
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [crypto?] KMSAN: uninit-value in poly1305_blocks

Hello,

syzbot found the following issue on:

HEAD commit:    211ddde0823f Linux 6.18-rc2
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11af9734580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bbd3e7f3c2e28265
dashboard link: https://syzkaller.appspot.com/bug?extid=01fcd39a0d90cdb0e3df
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=11099492580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1096eb04580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46c24dbd5a18/disk-211ddde0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4d12e20e76d7/vmlinux-211ddde0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9e4b9dd5db28/bzImage-211ddde0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01fcd39a0d90cdb0e3df@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in poly1305_blocks+0x1a9/0x5f0 lib/crypto/x86/poly1305.h:110
 poly1305_blocks+0x1a9/0x5f0 lib/crypto/x86/poly1305.h:110
 poly1305_update+0x169/0x400 lib/crypto/poly1305.c:50
 poly_hash+0x9f3/0x1a00 crypto/chacha20poly1305.c:168
 poly_genkey+0x3b6/0x450 crypto/chacha20poly1305.c:233
 chacha_encrypt crypto/chacha20poly1305.c:269 [inline]
 chachapoly_encrypt+0x48a/0x5c0 crypto/chacha20poly1305.c:284
 crypto_aead_encrypt+0xe2/0x160 crypto/aead.c:91
 tls_do_encryption net/tls/tls_sw.c:582 [inline]
 tls_push_record+0x38c7/0x5810 net/tls/tls_sw.c:819
 bpf_exec_tx_verdict+0x1a0c/0x26a0 net/tls/tls_sw.c:859
 tls_sw_sendmsg_locked net/tls/tls_sw.c:1138 [inline]
 tls_sw_sendmsg+0x3401/0x4560 net/tls/tls_sw.c:1281
 inet6_sendmsg+0x26c/0x2a0 net/ipv6/af_inet6.c:659
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x3d0 net/socket.c:742
 sock_write_iter+0x3a6/0x420 net/socket.c:1195
 do_iter_readv_writev+0x9e1/0xc20 fs/read_write.c:-1
 vfs_writev+0x52a/0x1500 fs/read_write.c:1057
 do_writev+0x1b5/0x580 fs/read_write.c:1103
 __do_sys_writev fs/read_write.c:1171 [inline]
 __se_sys_writev fs/read_write.c:1168 [inline]
 __x64_sys_writev+0x99/0xf0 fs/read_write.c:1168
 x64_sys_call+0x24b1/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:21
 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

Local variable desc created at:
 poly_hash+0x11d/0x1a00 crypto/chacha20poly1305.c:135
 poly_genkey+0x3b6/0x450 crypto/chacha20poly1305.c:233

CPU: 1 UID: 0 PID: 6030 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none) 
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:
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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