linux-kernel - [PATCH] lib/crypto: poly1305: fix uninit-value in poly1305

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Message-Id: <751b3d80293a6f599bb07770afcef24f623c7da0.1761026343.git.xiaopei01@kylinos.cn>
Date: Tue, 21 Oct 2025 14:01:20 +0800
From: Pei Xiao <xiaopei01@...inos.cn>
To: ebiggers@...nel.org,
	Jason@...c4.com,
	ardb@...nel.org,
	ubizjak@...il.com,
	linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Pei Xiao <xiaopei01@...inos.cn>,
	syzbot+01fcd39a0d90cdb0e3df@...kaller.appspotmail.com
Subject: [PATCH] lib/crypto: poly1305: fix uninit-value in poly1305_blocks

syzbot reports uninit-value in poly1305_blocks:

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

in poly1305_blocks, ctx->is_base2_26 is uninit-value, ctx init in：
poly1305_init ->
     poly1305_block_init

so add memset in poly1305_block_init, then use poly1305_init_x86_64 to init
by asm.

Reported-by: syzbot+01fcd39a0d90cdb0e3df@...kaller.appspotmail.com
Tested-by: syzbot+01fcd39a0d90cdb0e3df@...kaller.appspotmail.com
Signed-off-by: Pei Xiao <xiaopei01@...inos.cn>
---
 lib/crypto/x86/poly1305.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/crypto/x86/poly1305.h b/lib/crypto/x86/poly1305.h
index ee92e3740a78..3b9f1024a18d 100644
--- a/lib/crypto/x86/poly1305.h
+++ b/lib/crypto/x86/poly1305.h
@@ -8,6 +8,7 @@
 #include <linux/jump_label.h>
 #include <linux/kernel.h>
 #include <linux/sizes.h>
+#include <linux/string.h>
 
 struct poly1305_arch_internal {
 	union {
@@ -86,6 +87,7 @@ static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx512);
 static void poly1305_block_init(struct poly1305_block_state *state,
 				const u8 raw_key[POLY1305_BLOCK_SIZE])
 {
+	memset(state, 0, sizeof(struct poly1305_block_state));
 	poly1305_init_x86_64(state, raw_key);
 }
 
-- 
2.25.1