tpm: fix a kernel memory leak in tpm-sysfs.c

commit 13b47cfcfc60495cde216eef4c01040d76174cbe upstream.

While cleaning up sysfs callback that prints EK we discovered a kernel
memory leak. This commit fixes the issue by zeroing the buffer used for
TPM command/response.

The leak happen when we use either tpm_vtpm_proxy, tpm_ibmvtpm or
xen-tpmfront.

Fixes: 0883743825e3 ("TPM: sysfs functions consolidation")
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index f7395c4..2c71cc4 100644 (file)
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -879,9 +879,10 @@ ssize_t tpm_show_pubek(struct device *dev, struct device_attribute *attr,
        ssize_t err;
        int i, rc;
        char *str = buf;
-
        struct tpm_chip *chip = dev_get_drvdata(dev);
 
+       memset(&tpm_cmd, 0, sizeof(tpm_cmd));
+
        tpm_cmd.header.in = tpm_readpubek_header;
        err = transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
                        "attempting to read the PUBEK");