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authorTim Gardner <tim.gardner@canonical.com>2011-12-06 11:29:20 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-04-02 09:52:37 -0700
commit923da1e9e292633437c35fd870d47f18b0ee197f (patch)
treebf4cbc80569796dcb80a890380f9b5e1f25a639d /drivers/char
parentc6cf24ba30c7225667827245cfd2bc98f7f5ed2b (diff)
TPM: Zero buffer whole after copying to userspace
commit 3ab1aff89477dafb1aaeafe8c8669114a02b7226 upstream. Commit 3321c07ae5068568cd61ac9f4ba749006a7185c9 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 Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tpm/tpm.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 361a1dff8f7..b366b34c854 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1115,12 +1115,13 @@ 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;