From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bedivere.hansenpartnership.com ([66.63.167.143]:59612 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752179AbeBHUcH (ORCPT ); Thu, 8 Feb 2018 15:32:07 -0500 Message-ID: <1518121926.21828.17.camel@HansenPartnership.com> Subject: [PATCH v2 5/5] tpm_tis: fix potential buffer overruns caused by bit glitches on the bus From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jeremy Boone , Jarkko Sakkinen Date: Thu, 08 Feb 2018 12:32:06 -0800 In-Reply-To: <1518121576.21828.10.camel@HansenPartnership.com> References: <1518121576.21828.10.camel@HansenPartnership.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org List-ID: From: Jeremy Boone Discrete TPMs are often connected over slow serial buses which, on some platforms, can have glitches causing bit flips. In all the driver _recv() functions, we need to use a u32 to unmarshal the response size, otherwise a bit flip of the 31st bit would cause the expected variable to go negative, which would then try to read a huge amount of data. Also sanity check that the expected amount of data is large enough for the TPM header. Signed-off-by: Jeremy Boone Cc: stable@vger.kernel.org Signed-off-by: James Bottomley --- drivers/char/tpm/tpm_tis_core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index fdde971bc810..7561922bc8f8 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -202,7 +202,8 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); int size = 0; - int expected, status; + int status; + u32 expected; if (count < TPM_HEADER_SIZE) { size = -EIO; @@ -217,7 +218,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) } expected = be32_to_cpu(*(__be32 *) (buf + 2)); - if (expected > count) { + if (expected > count || expected < TPM_HEADER_SIZE) { size = -EIO; goto out; } -- 2.12.3