linux-kernel - [PATCH] dmaengine: idxd: Fix potential null dereference on pointer status

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Message-Id: <20210415110654.1941580-1-colin.king@canonical.com>
Date:   Thu, 15 Apr 2021 12:06:54 +0100
From:   Colin King <colin.king@...onical.com>
To:     Dave Jiang <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>,
        dmaengine@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] dmaengine: idxd: Fix potential null dereference on pointer status

From: Colin Ian King <colin.king@...onical.com>

There are calls to idxd_cmd_exec that pass a null status pointer however
a recent commit has added an assignment to *status that can end up
with a null pointer dereference.  The function expects a null status
pointer sometimes as there is a later assignment to *status where
status is first null checked.  Fix the issue by null checking status
before making the assignment.

Addresses-Coverity: ("Explicit null dereferenced")
Fixes: 89e3becd8f82 ("dmaengine: idxd: check device state before issue command")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/dma/idxd/device.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 31c819544a22..78d2dc5e9bd8 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -451,7 +451,8 @@ static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
 
 	if (idxd_device_is_halted(idxd)) {
 		dev_warn(&idxd->pdev->dev, "Device is HALTED!\n");
-		*status = IDXD_CMDSTS_HW_ERR;
+		if (status)
+			*status = IDXD_CMDSTS_HW_ERR;
 		return;
 	}
 
-- 
2.30.2