[PATCH v2] ide: Check for null pointer after calling devm_ioremap

[PATCH v2] ide: Check for null pointer after calling devm_ioremap

[Jiasheng Jiang]

As the possible failure of the devres_alloc(), the devm_ioremap() and
devm_ioport_map() may return NULL pointer.
And then, the 'base' and 'alt_base' is used in plat_ide_setup_ports().
Therefore, it should be better to add the check in order to avoid the
dereference of the NULL pointer.

Fixes: 2bfba3c444fe ("ide: remove useless subdirs from drivers/ide/")
Cc: 5.10
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Add cc.
---
 drivers/ide/ide_platform.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/ide/ide_platform.c b/drivers/ide/ide_platform.c
index 91639fd6c276..8c6e1af7b6eb 100644
--- a/drivers/ide/ide_platform.c
+++ b/drivers/ide/ide_platform.c
@@ -85,6 +85,10 @@ static int plat_ide_probe(struct platform_device *pdev)
 		alt_base = devm_ioport_map(&pdev->dev,
 			res_alt->start, resource_size(res_alt));
 	}
+	if (!base || !alt_base) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	memset(&hw, 0, sizeof(hw));
 	plat_ide_setup_ports(&hw, base, alt_base, pdata, res_irq->start);
-- 
2.25.1

Re: [PATCH v2] ide: Check for null pointer after calling devm_ioremap

[Damien Le Moal]

On 1/7/22 16:04, Jiasheng Jiang wrote:
> As the possible failure of the devres_alloc(), the devm_ioremap() and
> devm_ioport_map() may return NULL pointer.
> And then, the 'base' and 'alt_base' is used in plat_ide_setup_ports().
> Therefore, it should be better to add the check in order to avoid the
> dereference of the NULL pointer.
> 
> Fixes: 2bfba3c444fe ("ide: remove useless subdirs from drivers/ide/")

This patch only renamed files under drivers/ide. I do not think it is
the patch that introduced the problem you are trying to fix.

> Cc: 5.10

Please read
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html?highlight=linux%20stable

> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> ---
> Changelog
> 
> v1 -> v2
> 
> * Change 1. Add cc.

Adding a CC to the distribution list of the patch does not change the
patch itself, so no need for tagging "v2".

> ---
>  drivers/ide/ide_platform.c | 4 ++++

Again, this file does NOT exist anymore.
The legacy IDE driver was removed from the kernel with version 5.14 by
commit b7fb14d3ac63 ("ide: remove the legacy ide driver"). libata now
implements drivers for legacy PATA/IDE drives. Have you checked first if
your fix is needed there ? If it is, then please send your patch against
the current libata tree. If the fix is needed only in older LTS kernels,
then please make that clear in a cover letter with your patch.

>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/ide/ide_platform.c b/drivers/ide/ide_platform.c
> index 91639fd6c276..8c6e1af7b6eb 100644
> --- a/drivers/ide/ide_platform.c
> +++ b/drivers/ide/ide_platform.c
> @@ -85,6 +85,10 @@ static int plat_ide_probe(struct platform_device *pdev)
>  		alt_base = devm_ioport_map(&pdev->dev,
>  			res_alt->start, resource_size(res_alt));
>  	}
> +	if (!base || !alt_base) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
>  
>  	memset(&hw, 0, sizeof(hw));
>  	plat_ide_setup_ports(&hw, base, alt_base, pdata, res_irq->start);


-- 
Damien Le Moal
Western Digital Research

[PATCH v2] ide: Check for null pointer after calling devm_ioremap

[Jiasheng Jiang]

In linux-stable-5.15.13, this file has been removed and combined
to `drivers/ata/pata_platform.c` without this bug.
But in the older LTS kernels, like 5.10.90, this bug still exists.
As the possible failure of the devres_alloc(), the devm_ioremap() and
devm_ioport_map() may return NULL pointer.
And then, the 'base' and 'alt_base' are used in plat_ide_setup_ports().
Therefore, it should be better to add the check in order to avoid the
dereference of the NULL pointer.
Actually, it introduced the bug from commit 8cb1f567f4c0
("ide: Platform IDE driver") and we can know from the commit message
that it tended to be similar to the `drivers/ata/pata_platform.c`.
But actually, even the first time pata_platform was built,
commit a20c9e820864 ("[PATCH] ata: Generic platform_device libata driver"),
there was no the bug, as there was a check after the ioremap().
So possibly the bug was caused by ide itself.

Fixes: 8cb1f567f4c0 ("ide: Platform IDE driver")
Cc: stable@vger.kernel.org#5.10.90
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Correct the fixes tag and commit message.
---
 drivers/ide/ide_platform.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/ide/ide_platform.c b/drivers/ide/ide_platform.c
index 91639fd6c276..5500c5afb3ca 100644
--- a/drivers/ide/ide_platform.c
+++ b/drivers/ide/ide_platform.c
@@ -85,6 +85,10 @@ static int plat_ide_probe(struct platform_device *pdev)
 		alt_base = devm_ioport_map(&pdev->dev,
 			res_alt->start, resource_size(res_alt));
 	}
+	if (!base || !!alt_base) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	memset(&hw, 0, sizeof(hw));
 	plat_ide_setup_ports(&hw, base, alt_base, pdata, res_irq->start);
-- 
2.25.1

RE: [PATCH v2] ide: Check for null pointer after calling devm_ioremap

[David Laight]

From: Jiasheng Jiang
> Sent: 07 January 2022 09:12
> 
> In linux-stable-5.15.13, this file has been removed and combined
> to `drivers/ata/pata_platform.c` without this bug.
> But in the older LTS kernels, like 5.10.90, this bug still exists.
> As the possible failure of the devres_alloc(), the devm_ioremap() and
> devm_ioport_map() may return NULL pointer.
> And then, the 'base' and 'alt_base' are used in plat_ide_setup_ports().
> Therefore, it should be better to add the check in order to avoid the
> dereference of the NULL pointer.
> Actually, it introduced the bug from commit 8cb1f567f4c0
> ("ide: Platform IDE driver") and we can know from the commit message
> that it tended to be similar to the `drivers/ata/pata_platform.c`.
> But actually, even the first time pata_platform was built,
> commit a20c9e820864 ("[PATCH] ata: Generic platform_device libata driver"),
> there was no the bug, as there was a check after the ioremap().
> So possibly the bug was caused by ide itself.
> 
> Fixes: 8cb1f567f4c0 ("ide: Platform IDE driver")
> Cc: stable@vger.kernel.org#5.10.90
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> ---
> Changelog
> 
> v1 -> v2
> 
> * Change 1. Correct the fixes tag and commit message.
> ---
>  drivers/ide/ide_platform.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/ide/ide_platform.c b/drivers/ide/ide_platform.c
> index 91639fd6c276..5500c5afb3ca 100644
> --- a/drivers/ide/ide_platform.c
> +++ b/drivers/ide/ide_platform.c
> @@ -85,6 +85,10 @@ static int plat_ide_probe(struct platform_device *pdev)
>  		alt_base = devm_ioport_map(&pdev->dev,
>  			res_alt->start, resource_size(res_alt));
>  	}
> +	if (!base || !!alt_base) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}

That !!alt_base doesn't look right.
Without looking at the rest of the code maybe:
	if (!base && !alt_base)
may be correct.

It also rather makes me wonder about the actual failure return value.
If devm_ioport_map() returns a 'port number' for inb()/outb() then
zero is technically a valid value!

	David

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