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TPM: Zero buffer whole after copying to userspace

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Commit 3321c07ae5 correctly clears the TPM
buffer if the user specified read length is >= the TPM buffer length. However,
if the user specified read length is < the TPM buffer length, then part of the
TPM buffer is left uncleared.

Reported-by: Seth Forshee <seth.forshee@canonical.com>
Cc: Debora Velarde <debora@linux.vnet.ibm.com>
Cc: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
Cc: Marcel Selhorst <m.selhorst@sirrix.com>
Cc: tpmdd-devel@lists.sourceforge.net
Cc: stable@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
This commit is contained in:
Tim Gardner 2011-12-06 11:29:20 -07:00 committed by Rajiv Andrade
parent 968de8e24d
commit 3ab1aff894
1 changed files with 2 additions and 1 deletions
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3
drivers/char/tpm/tpm.c
View file

@ -1221,12 +1221,13 @@ ssize_t tpm_read(struct file *file, char __user *buf,
ret_size = atomic_read(&chip->data_pending);
atomic_set(&chip->data_pending, 0);
if (ret_size > 0) { /* relay data */
ssize_t orig_ret_size = ret_size;
if (size < ret_size)
ret_size = size;
mutex_lock(&chip->buffer_mutex);
rc = copy_to_user(buf, chip->data_buffer, ret_size);
memset(chip->data_buffer, 0, ret_size);
memset(chip->data_buffer, 0, orig_ret_size);
if (rc)
ret_size = -EFAULT;