On 10/27/24 2:53 AM, Suraj Sonawane wrote:
Fix an issue detected by the Smatch static tool: drivers/greybus/operation.c:852 gb_operation_response_send() error: we previously assumed 'operation->response' could be null (see line 829)
There is no need for this. This is a case where the code is doing something that is too involved for "smatch" to know things are OK.
A unidirectional operation includes only a request message, but no response message.
There are two cases: - Unidirectional - There is no response buffer - There will be no call to gb_operation_response_alloc(), because the operation is unidirectional. - The result gets set with the errno value. If there's an error (there shouldn't be), -EIO is returned. - We return 0 early, because it's a unidirectional operation. - Not unidirectional - If there is a response, we attempt to allocate one. If that fails, we return -ENOMEM early. - Otherwise there *is* a response (it was successfully allocated) - The result is set - It is not unidirectional, so we get a reference to the operation, add it to the active list (or skip to the end if not connected) - We record the result in the response header. This is the line in question, but we know the response pointer is good. - We send the response. - On error, we drop or references and return the error code.
-Alex
The issue occurs because 'operation->response' may be null if the response allocation fails at line 829. However, the code tries to access 'operation->response->header' at line 852 without checking if it was successfully allocated. This can cause a crash if 'response' is null.
To fix this, add a check to ensure 'operation->response' is not null before accessing its header. If the response is null, log an error message and return -ENOMEM to stop further processing, preventing any crashes or undefined behavior.
Signed-off-by: Suraj Sonawane surajsonawane0215@gmail.com
drivers/greybus/operation.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/greybus/operation.c b/drivers/greybus/operation.c index 8459e9bc0..521899fbc 100644 --- a/drivers/greybus/operation.c +++ b/drivers/greybus/operation.c @@ -849,7 +849,13 @@ static int gb_operation_response_send(struct gb_operation *operation, goto err_put; /* Fill in the response header and send it */
- operation->response->header->result = gb_operation_errno_map(errno);
- if (operation->response) {
operation->response->header->result = gb_operation_errno_map(errno);- } else {
dev_err(&connection->hd->dev, "failed to allocate response\n");ret = -ENOMEM;goto err_put_active;- }
ret = gb_message_send(operation->response, GFP_KERNEL); if (ret)