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[62.108.10.193]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c15bc428775sm581447866b.6.2026.07.10.10.29.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2026 10:29:35 -0700 (PDT) Date: Fri, 10 Jul 2026 19:29:33 +0200 From: "David C.C.M. Gall" To: Lukas Wunner , Ignat Korchagin , Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org Subject: [PATCH] crypto: rsassa-pkcs1: use constant-time comparison for digest and signature verification Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Replace memcmp() with crypto_memneq() for cryptographic digest and signature comparisons to prevent timing side-channel attacks. crypto/rsassa-pkcs1.c: RSA signature digest verification used memcmp which can leak valid prefix length via timing analysis, user data could reach the leaky comparison via the digest argument to verify. Assisted-by: gregkh_clanker_t1000 Signed-off-by: David C.C.M. Gall --- crypto/rsassa-pkcs1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c index 94fa5e9600e7..a612a9eef2dd 100644 --- a/crypto/rsassa-pkcs1.c +++ b/crypto/rsassa-pkcs1.c @@ -291,7 +291,7 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm, /* RFC 8017 sec 8.2.2 step 4 - comparison of digest with out_buf */ if (dlen != dst_len - pos) return -EKEYREJECTED; - if (memcmp(digest, out_buf + pos, dlen) != 0) + if (crypto_memneq(digest, out_buf + pos, dlen)) return -EKEYREJECTED; return 0; -- 2.43.0