The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5df16caada3fba3b21cb09b85cdedf99507f4ec1 Mon Sep 17 00:00:00 2001

From: Jarkko Sakkinen jarkko@kernel.org Date: Fri, 29 Jan 2021 01:56:19 +0200 Subject: [PATCH] KEYS: trusted: Fix incorrect handling of tpm_get_random()

When tpm_get_random() was introduced, it defined the following API for the return value:

1. A positive value tells how many bytes of random data was generated. 2. A negative value on error.

However, in the call sites the API was used incorrectly, i.e. as it would only return negative values and otherwise zero. Returning he positive read counts to the user space does not make any possible sense.

Fix this by returning -EIO when tpm_get_random() returns a positive value.

Fixes: 41ab999c80f1 ("tpm: Move tpm_get_random api into the TPM device driver") Cc: stable@vger.kernel.org Cc: Mimi Zohar zohar@linux.ibm.com Cc: "James E.J. Bottomley" James.Bottomley@HansenPartnership.com Cc: David Howells dhowells@redhat.com Cc: Kent Yoder key@linux.vnet.ibm.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Reviewed-by: Mimi Zohar zohar@linux.ibm.com

diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c index 74d82093cbaa..204826b734ac 100644 --- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -403,9 +403,12 @@ static int osap(struct tpm_buf *tb, struct osapsess *s, int ret;

ret = tpm_get_random(chip, ononce, TPM_NONCE_SIZE); - if (ret != TPM_NONCE_SIZE) + if (ret < 0) return ret;

+ if (ret != TPM_NONCE_SIZE) + return -EIO; + tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP); tpm_buf_append_u16(tb, type); tpm_buf_append_u32(tb, handle); @@ -496,8 +499,12 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype, goto out;

ret = tpm_get_random(chip, td->nonceodd, TPM_NONCE_SIZE); + if (ret < 0) + return ret; + if (ret != TPM_NONCE_SIZE) - goto out; + return -EIO; + ordinal = htonl(TPM_ORD_SEAL); datsize = htonl(datalen); pcrsize = htonl(pcrinfosize); @@ -601,9 +608,12 @@ static int tpm_unseal(struct tpm_buf *tb,

ordinal = htonl(TPM_ORD_UNSEAL); ret = tpm_get_random(chip, nonceodd, TPM_NONCE_SIZE); + if (ret < 0) + return ret; + if (ret != TPM_NONCE_SIZE) { pr_info("trusted_key: tpm_get_random failed (%d)\n", ret); - return ret; + return -EIO; } ret = TSS_authhmac(authdata1, keyauth, TPM_NONCE_SIZE, enonce1, nonceodd, cont, sizeof(uint32_t), @@ -1013,8 +1023,12 @@ static int trusted_instantiate(struct key *key, case Opt_new: key_len = payload->key_len; ret = tpm_get_random(chip, payload->key, key_len); + if (ret < 0) + goto out; + if (ret != key_len) { pr_info("trusted_key: key_create failed (%d)\n", ret); + ret = -EIO; goto out; } if (tpm2)