linux-kernel - [PATCH] greybus: Fix null pointer dereference in gb_operation_response

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Message-Id: <20241027075304.7301-1-surajsonawane0215@gmail.com>
Date: Sun, 27 Oct 2024 13:23:04 +0530
From: Suraj Sonawane <surajsonawane0215@...il.com>
To: johan@...nel.org,
	elder@...nel.org,
	gregkh@...uxfoundation.org
Cc: greybus-dev@...ts.linaro.org,
	linux-kernel@...r.kernel.org,
	Suraj Sonawane <surajsonawane0215@...il.com>
Subject: [PATCH] greybus: Fix null pointer dereference in gb_operation_response_send()

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)

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@...il.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)
-- 
2.34.1