From ee70bc1e7b63ac8023c9ff9475d8741e397316e7 Mon Sep 17 00:00:00 2001 From: Alexander Steffen Date: Fri, 8 Sep 2017 17:21:32 +0200 Subject: [PATCH] tpm-dev-common: Reject too short writes tpm_transmit() does not offer an explicit interface to indicate the number of valid bytes in the communication buffer. Instead, it relies on the commandSize field in the TPM header that is encoded within the buffer. Therefore, ensure that a) enough data has been written to the buffer, so that the commandSize field is present and b) the commandSize field does not announce more data than has been written to the buffer. This should have been fixed with CVE-2011-1161 long ago, but apparently a correct version of that patch never made it into the kernel. Cc: stable@vger.kernel.org Signed-off-by: Alexander Steffen Reviewed-by: Jarkko Sakkinen Tested-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-dev-common.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 610638a..461bf0b 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -110,6 +110,12 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, return -EFAULT; } + if (in_size < 6 || + in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) { + mutex_unlock(&priv->buffer_mutex); + return -EINVAL; + } + /* atomic tpm command send and result receive. We only hold the ops * lock during this period so that the tpm can be unregistered even if * the char dev is held open. -- 2.7.4