diff mbox series

platform/mellanox: mlxreg-hotplug: Check pointer for NULL before dereferencing it

Message ID 20240226145442.3468-1-d.dulov@aladdin.ru
State New
Headers
Series platform/mellanox: mlxreg-hotplug: Check pointer for NULL before dereferencing it |

Commit Message

Daniil Dulov Feb. 26, 2024, 2:54 p.m. UTC 
  mlxreg_hotplug_work_helper() implies that item can be NULL. There is a
sanity check that checks item for NULL and then dereferences it.

Even though, the comment before sanity check says that it can only happen
if some piece of hardware is broken, but in this case it will lead to
NULL-pointer dereference before the function is even called,
so let's check it before dereferencing.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c6acad68eb2d ("platform/mellanox: mlxreg-hotplug: Modify to use a regmap interface")
Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
---
 drivers/platform/mellanox/mlxreg-hotplug.c | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

Comments

Daniil Dulov March 4, 2024, 11:43 a.m. UTC | #1 
Hello!

I suppose there is no sense to produce dev_err() inside
mlxreg_hotplug_work_helper() since item is dereferenced twice
before we call this function. Should we produce dev_err()
inside the loop in mlxreg_hotplug_work_handler() instead?

-----Original Message-----
From: Vadim Pasternak [mailto:vadimp@nvidia.com] 
Sent: Monday, February 26, 2024 6:15 PM
To: Daniil Dulov <D.Dulov@aladdin.ru>; Hans de Goede <hdegoede@redhat.com>
Cc: Mark Gross <mgross@linux.intel.com>; Andy Shevchenko <andy@infradead.org>; Darren Hart <dvhart@infradead.org>; platform-driver-x86@vger.kernel.org; linux-kernel@vger.kernel.org; lvc-project@linuxtesting.org
Subject: RE: [PATCH] platform/mellanox: mlxreg-hotplug: Check pointer for NULL before dereferencing it



> -----Original Message-----
> From: Daniil Dulov <d.dulov@aladdin.ru>
> Sent: Monday, 26 February 2024 16:55
> To: Hans de Goede <hdegoede@redhat.com>
> Cc: Daniil Dulov <d.dulov@aladdin.ru>; Mark Gross
> <mgross@linux.intel.com>; Andy Shevchenko <andy@infradead.org>; Darren
> Hart <dvhart@infradead.org>; Vadim Pasternak <vadimp@nvidia.com>;
> platform-driver-x86@vger.kernel.org; linux-kernel@vger.kernel.org; lvc-
> project@linuxtesting.org
> Subject: [PATCH] platform/mellanox: mlxreg-hotplug: Check pointer for NULL
> before dereferencing it
> 
> mlxreg_hotplug_work_helper() implies that item can be NULL. There is a
> sanity check that checks item for NULL and then dereferences it.
> 
> Even though, the comment before sanity check says that it can only happen if
> some piece of hardware is broken, but in this case it will lead to NULL-pointer
> dereference before the function is even called, so let's check it before
> dereferencing.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: c6acad68eb2d ("platform/mellanox: mlxreg-hotplug: Modify to use a
> regmap interface")
> Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
> ---
>  drivers/platform/mellanox/mlxreg-hotplug.c | 16 +---------------
>  1 file changed, 1 insertion(+), 15 deletions(-)
> 
> diff --git a/drivers/platform/mellanox/mlxreg-hotplug.c
> b/drivers/platform/mellanox/mlxreg-hotplug.c
> index 5c022b258f91..524121b9f070 100644
> --- a/drivers/platform/mellanox/mlxreg-hotplug.c
> +++ b/drivers/platform/mellanox/mlxreg-hotplug.c
> @@ -348,20 +348,6 @@ mlxreg_hotplug_work_helper(struct
> mlxreg_hotplug_priv_data *priv,
>  	u32 regval, bit;
>  	int ret;
> 
> -	/*
> -	 * Validate if item related to received signal type is valid.
> -	 * It should never happen, excepted the situation when some
> -	 * piece of hardware is broken. In such situation just produce
> -	 * error message and return. Caller must continue to handle the
> -	 * signals from other devices if any.
> -	 */
> -	if (unlikely(!item)) {
> -		dev_err(priv->dev, "False signal: at offset:mask
> 0x%02x:0x%02x.\n",
> -			item->reg, item->mask);
> -
> -		return;
> -	}

It would be enough just to produce dev_err(priv->dev, "False signal\n");
And return.

> -
>  	/* Mask event. */
>  	ret = regmap_write(priv->regmap, item->reg +
> MLXREG_HOTPLUG_MASK_OFF,
>  			   0);
> @@ -556,7 +542,7 @@ static void mlxreg_hotplug_work_handler(struct
> work_struct *work)
> 
>  	/* Handle topology and health configuration changes. */
>  	for (i = 0; i < pdata->counter; i++, item++) {
> -		if (aggr_asserted & item->aggr_mask) {
> +		if (item && (aggr_asserted & item->aggr_mask)) {
>  			if (item->health)
>  				mlxreg_hotplug_health_work_helper(priv,
> item);
>  			else
> --
> 2.25.1
diff mbox series

Patch

diff --git a/drivers/platform/mellanox/mlxreg-hotplug.c b/drivers/platform/mellanox/mlxreg-hotplug.c
index 5c022b258f91..524121b9f070 100644
--- a/drivers/platform/mellanox/mlxreg-hotplug.c
+++ b/drivers/platform/mellanox/mlxreg-hotplug.c
@@ -348,20 +348,6 @@  mlxreg_hotplug_work_helper(struct mlxreg_hotplug_priv_data *priv,
 	u32 regval, bit;
 	int ret;
 
-	/*
-	 * Validate if item related to received signal type is valid.
-	 * It should never happen, excepted the situation when some
-	 * piece of hardware is broken. In such situation just produce
-	 * error message and return. Caller must continue to handle the
-	 * signals from other devices if any.
-	 */
-	if (unlikely(!item)) {
-		dev_err(priv->dev, "False signal: at offset:mask 0x%02x:0x%02x.\n",
-			item->reg, item->mask);
-
-		return;
-	}
-
 	/* Mask event. */
 	ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_MASK_OFF,
 			   0);
@@ -556,7 +542,7 @@  static void mlxreg_hotplug_work_handler(struct work_struct *work)
 
 	/* Handle topology and health configuration changes. */
 	for (i = 0; i < pdata->counter; i++, item++) {
-		if (aggr_asserted & item->aggr_mask) {
+		if (item && (aggr_asserted & item->aggr_mask)) {
 			if (item->health)
 				mlxreg_hotplug_health_work_helper(priv, item);
 			else