5.15-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@kernel.org
commit eed0e3d305530066b4fc5370107cff8ef1a0d229 upstream.
To prevent timing attacks, HMAC value comparison needs to be constant time. Replace the memcmp() with the correct function, crypto_memneq().
[For the Fixes commit I used the commit that introduced the memcmp(). It predates the introduction of crypto_memneq(), but it was still a bug at the time even though a helper function didn't exist yet.]
Fixes: d00a1c72f7f4 ("keys: add new trusted key-type") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers ebiggers@kernel.org Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/keys/trusted-keys/trusted_tpm1.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -7,6 +7,7 @@ */
#include <crypto/hash_info.h> +#include <crypto/algapi.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/parser.h> @@ -241,7 +242,7 @@ int TSS_checkhmac1(unsigned char *buffer if (ret < 0) goto out;
- if (memcmp(testhmac, authdata, SHA1_DIGEST_SIZE)) + if (crypto_memneq(testhmac, authdata, SHA1_DIGEST_SIZE)) ret = -EINVAL; out: kfree_sensitive(sdesc); @@ -334,7 +335,7 @@ static int TSS_checkhmac2(unsigned char TPM_NONCE_SIZE, ononce, 1, continueflag1, 0, 0); if (ret < 0) goto out; - if (memcmp(testhmac1, authdata1, SHA1_DIGEST_SIZE)) { + if (crypto_memneq(testhmac1, authdata1, SHA1_DIGEST_SIZE)) { ret = -EINVAL; goto out; } @@ -343,7 +344,7 @@ static int TSS_checkhmac2(unsigned char TPM_NONCE_SIZE, ononce, 1, continueflag2, 0, 0); if (ret < 0) goto out; - if (memcmp(testhmac2, authdata2, SHA1_DIGEST_SIZE)) + if (crypto_memneq(testhmac2, authdata2, SHA1_DIGEST_SIZE)) ret = -EINVAL; out: kfree_sensitive(sdesc);