linux-kernel - [PATCH AUTOSEL 4.9 17/24] ipmi:ssif: Check for NULL msg when handling events and messages

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Message-Id: <20220530135211.1937674-17-sashal@kernel.org>
Date:   Mon, 30 May 2022 09:52:04 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Corey Minyard <cminyard@...sta.com>,
        Haowen Bai <baihaowen@...zu.com>,
        Sasha Levin <sashal@...nel.org>,
        openipmi-developer@...ts.sourceforge.net
Subject: [PATCH AUTOSEL 4.9 17/24] ipmi:ssif: Check for NULL msg when handling events and messages

From: Corey Minyard <cminyard@...sta.com>

[ Upstream commit 7602b957e2404e5f98d9a40b68f1fd27f0028712 ]

Even though it's not possible to get into the SSIF_GETTING_MESSAGES and
SSIF_GETTING_EVENTS states without a valid message in the msg field,
it's probably best to be defensive here and check and print a log, since
that means something else went wrong.

Also add a default clause to that switch statement to release the lock
and print a log, in case the state variable gets messed up somehow.

Reported-by: Haowen Bai <baihaowen@...zu.com>
Signed-off-by: Corey Minyard <cminyard@...sta.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/char/ipmi/ipmi_ssif.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
index a4ef9a6bd367..45117728e735 100644
--- a/drivers/char/ipmi/ipmi_ssif.c
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -812,6 +812,14 @@ static void msg_done_handler(struct ssif_info *ssif_info, int result,
 		break;
 
 	case SSIF_GETTING_EVENTS:
+		if (!msg) {
+			/* Should never happen, but just in case. */
+			dev_warn(&ssif_info->client->dev,
+				 "No message set while getting events\n");
+			ipmi_ssif_unlock_cond(ssif_info, flags);
+			break;
+		}
+
 		if ((result < 0) || (len < 3) || (msg->rsp[2] != 0)) {
 			/* Error getting event, probably done. */
 			msg->done(msg);
@@ -835,6 +843,14 @@ static void msg_done_handler(struct ssif_info *ssif_info, int result,
 		break;
 
 	case SSIF_GETTING_MESSAGES:
+		if (!msg) {
+			/* Should never happen, but just in case. */
+			dev_warn(&ssif_info->client->dev,
+				 "No message set while getting messages\n");
+			ipmi_ssif_unlock_cond(ssif_info, flags);
+			break;
+		}
+
 		if ((result < 0) || (len < 3) || (msg->rsp[2] != 0)) {
 			/* Error getting event, probably done. */
 			msg->done(msg);
@@ -857,6 +873,13 @@ static void msg_done_handler(struct ssif_info *ssif_info, int result,
 			deliver_recv_msg(ssif_info, msg);
 		}
 		break;
+
+	default:
+		/* Should never happen, but just in case. */
+		dev_warn(&ssif_info->client->dev,
+			 "Invalid state in message done handling: %d\n",
+			 ssif_info->ssif_state);
+		ipmi_ssif_unlock_cond(ssif_info, flags);
 	}
 
 	flags = ipmi_ssif_lock_cond(ssif_info, &oflags);
-- 
2.35.1