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: [email protected] Fixes: d23d124 ("tpm: fix invalid locking in NONBLOCKING mode") Reported-by: Laura Abbott <[email protected]> Signed-off-by: Tadeusz Struk <[email protected]> Reviewed-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Jarkko Sakkinen <[email protected]>
jbg · Jan 8, 2020 · a430e67 · a430e67
1 parent ae60882
commit a430e67
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diff --git 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
@@ -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;