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SubjectRe: [PATCH] KEYS: trusted: fix -Wvarags warning
On Thu, Oct 11, 2018 at 01:31:26PM -0700, ndesaulniers@google.com wrote:
> 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, ...)

Prototype needs to be updated in include/keys/trusted.h and it looks
like this function is used in crypto/asymmetric_keys/asym_tpm.c so these
same changes should be made there.

Otherwise, looks good to me! Thanks for sending the patch.

Nathan

> {
> 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
>

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