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Date:   Thu, 11 Oct 2018 13:31:26 -0700
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Message-Id: <20181011203126.15338-1-ndesaulniers@google.com>
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Subject: [PATCH] KEYS: trusted: fix -Wvarags warning
From:   ndesaulniers@google.com
To:     jejb@linux.vnet.ibm.com, dhowells@redhat.com
Cc:     natechancellor@gmail.com, ebiggers@google.com,
        Nick Desaulniers <ndesaulniers@google.com>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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by swapping h2 and h3.

security/keys/trusted.c:146:17: warning: passing an object that
undergoes default
      argument promotion to 'va_start' has undefined behavior [-Wvarargs]
        va_start(argp, h3);
                       ^
security/keys/trusted.c:126:37: note: parameter of type 'unsigned
char' is declared here
unsigned char *h2, unsigned char h3, ...)
                               ^

Specifically, it seems that both the C90 (4.8.1.1) and C11 (7.16.1.4)
standards explicitly call this out as undefined behavior:

The parameter parmN is the identifier of the rightmost parameter in
the variable parameter list in the function definition (the one just
before the ...). If the parameter parmN is declared with ... or with a
type that is not compatible with the type that results after
application of the default argument promotions, the behavior is
undefined.

Link: https://github.com/ClangBuiltLinux/linux/issues/41
Suggested-by: James Bottomley <jejb@linux.vnet.ibm.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 security/keys/trusted.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index b69d3b1777c2..d425b2b839af 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -123,7 +123,7 @@ static int TSS_rawhmac(unsigned char *digest, const unsigned char *key,
  */
 static int TSS_authhmac(unsigned char *digest, const unsigned char *key,
 			unsigned int keylen, unsigned char *h1,
-			unsigned char *h2, unsigned char h3, ...)
+			unsigned char h2, unsigned char *h3, ...)
 {
 	unsigned char paramdigest[SHA1_DIGEST_SIZE];
 	struct sdesc *sdesc;
@@ -139,7 +139,7 @@ static int TSS_authhmac(unsigned char *digest, const unsigned char *key,
 		return PTR_ERR(sdesc);
 	}
 
-	c = h3;
+	c = h2;
 	ret = crypto_shash_init(&sdesc->shash);
 	if (ret < 0)
 		goto out;
@@ -163,7 +163,7 @@ static int TSS_authhmac(unsigned char *digest, const unsigned char *key,
 	if (!ret)
 		ret = TSS_rawhmac(digest, key, keylen, SHA1_DIGEST_SIZE,
 				  paramdigest, TPM_NONCE_SIZE, h1,
-				  TPM_NONCE_SIZE, h2, 1, &c, 0, 0);
+				  TPM_NONCE_SIZE, h3, 1, &c, 0, 0);
 out:
 	kzfree(sdesc);
 	return ret;
@@ -508,7 +508,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 	if (pcrinfosize == 0) {
 		/* no pcr info specified */
 		ret = TSS_authhmac(td->pubauth, sess.secret, SHA1_DIGEST_SIZE,
-				   sess.enonce, td->nonceodd, cont,
+				   sess.enonce, cont, td->nonceodd,
 				   sizeof(uint32_t), &ordinal, SHA1_DIGEST_SIZE,
 				   td->encauth, sizeof(uint32_t), &pcrsize,
 				   sizeof(uint32_t), &datsize, datalen, data, 0,
@@ -516,7 +516,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 	} else {
 		/* pcr info specified */
 		ret = TSS_authhmac(td->pubauth, sess.secret, SHA1_DIGEST_SIZE,
-				   sess.enonce, td->nonceodd, cont,
+				   sess.enonce, cont, td->nonceodd,
 				   sizeof(uint32_t), &ordinal, SHA1_DIGEST_SIZE,
 				   td->encauth, sizeof(uint32_t), &pcrsize,
 				   pcrinfosize, pcrinfo, sizeof(uint32_t),
@@ -608,12 +608,12 @@ static int tpm_unseal(struct tpm_buf *tb,
 		return ret;
 	}
 	ret = TSS_authhmac(authdata1, keyauth, TPM_NONCE_SIZE,
-			   enonce1, nonceodd, cont, sizeof(uint32_t),
+			   enonce1, cont, nonceodd, sizeof(uint32_t),
 			   &ordinal, bloblen, blob, 0, 0);
 	if (ret < 0)
 		return ret;
 	ret = TSS_authhmac(authdata2, blobauth, TPM_NONCE_SIZE,
-			   enonce2, nonceodd, cont, sizeof(uint32_t),
+			   enonce2, cont, nonceodd, sizeof(uint32_t),
 			   &ordinal, bloblen, blob, 0, 0);
 	if (ret < 0)
 		return ret;
-- 
2.19.0.605.g01d371f741-goog