tpm: Handle negative priv->response_len in tpm_common_read()

The priv->response_length can hold the size of an response or an negative
error code, and the tpm_common_read() needs to handle both cases correctly.
Changed the type of response_length to signed and accounted for negative
value in tpm_common_read().

Cc: stable@vger.kernel.org
Fixes: d23d12484307 ("tpm: fix invalid locking in NONBLOCKING mode")
Reported-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index b23b0b9..87f4493 100644 (file)
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -130,7 +130,7 @@ ssize_t tpm_common_read(struct file *file, char __user *buf,
                priv->response_read = true;
 
                ret_size = min_t(ssize_t, size, priv->response_length);
-               if (!ret_size) {
+               if (ret_size <= 0) {
                        priv->response_length = 0;
                        goto out;
                }

diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h
index 1089fc0..f3742bc 100644 (file)
--- a/drivers/char/tpm/tpm-dev.h
+++ b/drivers/char/tpm/tpm-dev.h
@@ -14,7 +14,7 @@ struct file_priv {
        struct work_struct timeout_work;
        struct work_struct async_work;
        wait_queue_head_t async_wait;
-       size_t response_length;
+       ssize_t response_length;
        bool response_read;
        bool command_enqueued;