linux-kernel - Re: [PATCH libcrypto 2/2] crypto: chacha20poly1305: statically check fixed array lengths

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Message-ID: <202511192000.TLYrcg0Z-lkp@intel.com>
Date: Wed, 19 Nov 2025 20:45:15 +0800
From: kernel test robot <lkp@...el.com>
To: "Jason A. Donenfeld" <Jason@...c4.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Eric Biggers <ebiggers@...nel.org>,
	Ard Biesheuvel <ardb@...nel.org>, Kees Cook <kees@...nel.org>,
	linux-crypto@...r.kernel.org
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
	LKML <linux-kernel@...r.kernel.org>,
	"Jason A. Donenfeld" <Jason@...c4.com>
Subject: Re: [PATCH libcrypto 2/2] crypto: chacha20poly1305: statically check
 fixed array lengths

Hi Jason,

kernel test robot noticed the following build warnings:

[auto build test WARNING on herbert-cryptodev-2.6/master]
[also build test WARNING on herbert-crypto-2.6/master ebiggers/libcrypto-next ebiggers/libcrypto-fixes linus/master linux/master v6.18-rc6 next-20251119]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jason-A-Donenfeld/crypto-chacha20poly1305-statically-check-fixed-array-lengths/20251119-011125
base:   https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master
patch link:    https://lore.kernel.org/r/20251118170240.689299-2-Jason%40zx2c4.com
patch subject: [PATCH libcrypto 2/2] crypto: chacha20poly1305: statically check fixed array lengths
config: loongarch-allmodconfig (https://download.01.org/0day-ci/archive/20251119/202511192000.TLYrcg0Z-lkp@intel.com/config)
compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project cd708029e0b2869e80abe31ddb175f7c35361f90)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251119/202511192000.TLYrcg0Z-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511192000.TLYrcg0Z-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/wireguard/cookie.c:193:2: warning: array argument is too small; contains 31 elements, callee requires at least 32 [-Warray-bounds]
     193 |         xchacha20poly1305_encrypt(dst->encrypted_cookie, cookie, COOKIE_LEN,
         |         ^
     194 |                                   macs->mac1, COOKIE_LEN, dst->nonce,
     195 |                                   checker->cookie_encryption_key);
         |                                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/crypto/chacha20poly1305.h:32:20: note: callee declares array parameter as static here
      32 |                                const u8 key[min_array_size(CHACHA20POLY1305_KEY_SIZE)]);
         |                                         ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from drivers/net/wireguard/cookie.c:6:
   In file included from drivers/net/wireguard/cookie.h:9:
   In file included from drivers/net/wireguard/messages.h:10:
   In file included from include/crypto/chacha20poly1305.h:11:
   In file included from include/linux/scatterlist.h:5:
   In file included from include/linux/string.h:382:
   include/linux/fortify-string.h:480:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
     480 |                         __write_overflow_field(p_size_field, size);
         |                         ^
   2 warnings generated.


vim +193 drivers/net/wireguard/cookie.c

e7096c131e5161 Jason A. Donenfeld 2019-12-09  179  
e7096c131e5161 Jason A. Donenfeld 2019-12-09  180  void wg_cookie_message_create(struct message_handshake_cookie *dst,
e7096c131e5161 Jason A. Donenfeld 2019-12-09  181  			      struct sk_buff *skb, __le32 index,
e7096c131e5161 Jason A. Donenfeld 2019-12-09  182  			      struct cookie_checker *checker)
e7096c131e5161 Jason A. Donenfeld 2019-12-09  183  {
e7096c131e5161 Jason A. Donenfeld 2019-12-09  184  	struct message_macs *macs = (struct message_macs *)
e7096c131e5161 Jason A. Donenfeld 2019-12-09  185  		((u8 *)skb->data + skb->len - sizeof(*macs));
e7096c131e5161 Jason A. Donenfeld 2019-12-09  186  	u8 cookie[COOKIE_LEN];
e7096c131e5161 Jason A. Donenfeld 2019-12-09  187  
e7096c131e5161 Jason A. Donenfeld 2019-12-09  188  	dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE);
e7096c131e5161 Jason A. Donenfeld 2019-12-09  189  	dst->receiver_index = index;
e7096c131e5161 Jason A. Donenfeld 2019-12-09  190  	get_random_bytes_wait(dst->nonce, COOKIE_NONCE_LEN);
e7096c131e5161 Jason A. Donenfeld 2019-12-09  191  
e7096c131e5161 Jason A. Donenfeld 2019-12-09  192  	make_cookie(cookie, skb, checker);
e7096c131e5161 Jason A. Donenfeld 2019-12-09 @193  	xchacha20poly1305_encrypt(dst->encrypted_cookie, cookie, COOKIE_LEN,
e7096c131e5161 Jason A. Donenfeld 2019-12-09  194  				  macs->mac1, COOKIE_LEN, dst->nonce,
e7096c131e5161 Jason A. Donenfeld 2019-12-09  195  				  checker->cookie_encryption_key);
e7096c131e5161 Jason A. Donenfeld 2019-12-09  196  }
e7096c131e5161 Jason A. Donenfeld 2019-12-09  197  

-- 
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