Re: [PATCH v3] fsi: Aspeed: Fix a potential double free

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On 1/9/22 1:56 PM, Christophe JAILLET wrote:
A struct device can never be devm_alloc()'ed.
Here, it is embedded in "struct fsi_master", and "struct fsi_master" is
embedded in "struct fsi_master_aspeed".

Since "struct device" is embedded, the data structure embedding it must be
released with the release function, as is already done here.

So use kzalloc() instead of devm_kzalloc() when allocating "aspeed" and
update all error handling branches accordingly.

This prevent a potential double free().

This also fix another issue if opb_readl() fails. Instead of a direct
return, it now jumps in the error handling path.

Fixes: 606397d67f41 ("fsi: Add ast2600 master driver")
Suggested-by: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

---
v2: Keep the release function which is correct
     s/devm_kzalloc()/kzalloc()/ instead

v3: Update the error handling path to free "aspeed" [Guenter Roeck]
     Fix another issue when opb_readl() fails [Guenter Roeck]

I hope that fixing both issues in the same patch is ok. It makes no sense
to me not to update the goto to the correct label if opb_readl() fails.
---
  drivers/fsi/fsi-master-aspeed.c | 17 +++++++++++------
  1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/fsi/fsi-master-aspeed.c b/drivers/fsi/fsi-master-aspeed.c
index 8606e55c1721..0bed2fab8055 100644
--- a/drivers/fsi/fsi-master-aspeed.c
+++ b/drivers/fsi/fsi-master-aspeed.c
@@ -542,25 +542,28 @@ static int fsi_master_aspeed_probe(struct platform_device *pdev)
  		return rc;
  	}
- aspeed = devm_kzalloc(&pdev->dev, sizeof(*aspeed), GFP_KERNEL);
+	aspeed = kzalloc(sizeof(*aspeed), GFP_KERNEL);
  	if (!aspeed)
  		return -ENOMEM;
aspeed->dev = &pdev->dev; aspeed->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(aspeed->base))
-		return PTR_ERR(aspeed->base);
+	if (IS_ERR(aspeed->base)) {
+		rc = PTR_ERR(aspeed->base);
+		goto err_free_aspeed;
+	}
aspeed->clk = devm_clk_get(aspeed->dev, NULL);
  	if (IS_ERR(aspeed->clk)) {
  		dev_err(aspeed->dev, "couldn't get clock\n");
-		return PTR_ERR(aspeed->clk);
+		rc = PTR_ERR(aspeed->clk);
+		goto err_free_aspeed;
  	}
  	rc = clk_prepare_enable(aspeed->clk);
  	if (rc) {
  		dev_err(aspeed->dev, "couldn't enable clock\n");
-		return rc;
+		goto err_free_aspeed;
  	}
rc = setup_cfam_reset(aspeed);
@@ -595,7 +598,7 @@ static int fsi_master_aspeed_probe(struct platform_device *pdev)
  	rc = opb_readl(aspeed, ctrl_base + FSI_MVER, &raw);
  	if (rc) {
  		dev_err(&pdev->dev, "failed to read hub version\n");
-		return rc;
+		goto err_release;
  	}
reg = be32_to_cpu(raw);
@@ -634,6 +637,8 @@ static int fsi_master_aspeed_probe(struct platform_device *pdev)
err_release:
  	clk_disable_unprepare(aspeed->clk);
+err_free_aspeed:
+	kfree(aspeed);
  	return rc;
  }




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