TPM: Call tpm_transmit with correct size

This patch changes the call of tpm_transmit by supplying the size of the
userspace buffer instead of TPM_BUFSIZE.

This got assigned CVE-2011-1161.

[The first hunk didn't make sense given one could expect
 way less data than TPM_BUFSIZE, so added tpm_transmit boundary
 check over bufsiz instead
 The last parameter of tpm_transmit() reflects the amount
 of data expected from the device, and not the buffer size
 being supplied to it. It isn't ideal to parse it directly,
 so we just set it to the maximum the input buffer can handle
 and let the userspace API to do such job.]

Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Cc: Stable Kernel <stable@kernel.org>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index caf8012ef47c..1fe979335835 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -383,6 +383,9 @@ static ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
         u32 count, ordinal;
         unsigned long stop;
 
+        if (bufsiz > TPM_BUFSIZE)
+                bufsiz = TPM_BUFSIZE;
+
         count = be32_to_cpu(*((__be32 *) (buf + 2)));
         ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
         if (count == 0)