From: Eric Biggers <ebiggers@kernel.org>
Date: Sat, 22 Nov 2025 19:42:02 +0000 (-0800)
Subject: lib/crypto: curve25519: Add at_least decoration to fixed-size array params
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2143d622cdf3bf93e61f2e0a728487bc871785e5;p=thirdparty%2Fkernel%2Flinux.git

lib/crypto: curve25519: Add at_least decoration to fixed-size array params

Add the at_least (i.e. 'static') decoration to the fixed-size array
parameters of the curve25519 library functions.  This causes clang to
warn when a too-small array of known size is passed.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: "Jason A. Donenfeld" <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20251122194206.31822-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---

diff --git a/include/crypto/curve25519.h b/include/crypto/curve25519.h
index db63a5577c004..2362b48f87411 100644
--- a/include/crypto/curve25519.h
+++ b/include/crypto/curve25519.h
@@ -13,24 +13,28 @@ enum curve25519_lengths {
 	CURVE25519_KEY_SIZE = 32
 };
 
-void curve25519_generic(u8 out[CURVE25519_KEY_SIZE],
-			const u8 scalar[CURVE25519_KEY_SIZE],
-			const u8 point[CURVE25519_KEY_SIZE]);
+void curve25519_generic(u8 out[at_least CURVE25519_KEY_SIZE],
+			const u8 scalar[at_least CURVE25519_KEY_SIZE],
+			const u8 point[at_least CURVE25519_KEY_SIZE]);
 
-bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE],
-			     const u8 secret[CURVE25519_KEY_SIZE],
-			     const u8 basepoint[CURVE25519_KEY_SIZE]);
+bool __must_check
+curve25519(u8 mypublic[at_least CURVE25519_KEY_SIZE],
+	   const u8 secret[at_least CURVE25519_KEY_SIZE],
+	   const u8 basepoint[at_least CURVE25519_KEY_SIZE]);
 
-bool __must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE],
-					     const u8 secret[CURVE25519_KEY_SIZE]);
+bool __must_check
+curve25519_generate_public(u8 pub[at_least CURVE25519_KEY_SIZE],
+			   const u8 secret[at_least CURVE25519_KEY_SIZE]);
 
-static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE])
+static inline void
+curve25519_clamp_secret(u8 secret[at_least CURVE25519_KEY_SIZE])
 {
 	secret[0] &= 248;
 	secret[31] = (secret[31] & 127) | 64;
 }
 
-static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE])
+static inline void
+curve25519_generate_secret(u8 secret[at_least CURVE25519_KEY_SIZE])
 {
 	get_random_bytes_wait(secret, CURVE25519_KEY_SIZE);
 	curve25519_clamp_secret(secret);