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authorTim Gardner <tim.gardner@canonical.com>2011-12-06 11:29:20 -0700
committerRajiv Andrade <srajiv@linux.vnet.ibm.com>2012-02-14 16:43:38 -0200
commit3ab1aff89477dafb1aaeafe8c8669114a02b7226 (patch)
treea8445d0ca44505db9f59620c92b9fe842f9304f0
parent968de8e24d08fcc425e112ca465d4688b89b777b (diff)
TPM: Zero buffer whole after copying to userspace
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 Cc: stable@vger.kernel.org Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>
-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 32362cf35b8..ad7c7320dd1 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -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;