2016-03-23 02:52:59

by Vladimir Zapolskiy

Subject: [PATCH v2] misc: sram: fix check of devm_ioremap*() return value

Both devm_ioremap() and devm_ioremap_wc() functions return either
a pointer to valid iomem region or NULL, check for IS_ERR() is improper
and may result in oops on error path. Now on error -ENOMEM is returned.

Fixes: 0ab163ad1ea0 ("misc: sram: switch to ioremap_wc from ioremap")
Signed-off-by: Vladimir Zapolskiy <[email protected]>
---
I add Fixes: tag for reference, but unfortunately the change can not
be cleanly applied to kernel versions liable to the problem.

Changes from v1 to v2:
- had to rebase on top of eb43e023130b ("misc: sram: add optional ioremap without write combining")
- slightly reworded the commit message and subject

v1 of the change: https://lkml.org/lkml/2016/3/6/202

drivers/misc/sram.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index 69cdabe..f84b53d 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -364,8 +364,8 @@ static int sram_probe(struct platform_device *pdev)
sram->virt_base = devm_ioremap(sram->dev, res->start, size);
else
sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
- if (IS_ERR(sram->virt_base))
- return PTR_ERR(sram->virt_base);
+ if (!sram->virt_base)
+ return -ENOMEM;

sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
NUMA_NO_NODE, NULL);
--
2.1.4

2016-04-18 01:12:29

by Vladimir Zapolskiy

Subject: Re: [PATCH v2] misc: sram: fix check of devm_ioremap*() return value

Hi Greg,

On 23.03.2016 04:52, Vladimir Zapolskiy wrote:
> Both devm_ioremap() and devm_ioremap_wc() functions return either
> a pointer to valid iomem region or NULL, check for IS_ERR() is improper
> and may result in oops on error path. Now on error -ENOMEM is returned.
>
> Fixes: 0ab163ad1ea0 ("misc: sram: switch to ioremap_wc from ioremap")
> Signed-off-by: Vladimir Zapolskiy <[email protected]>
> ---
> I add Fixes: tag for reference, but unfortunately the change can not
> be cleanly applied to kernel versions liable to the problem.
>
> Changes from v1 to v2:
> - had to rebase on top of eb43e023130b ("misc: sram: add optional ioremap without write combining")
> - slightly reworded the commit message and subject
>
> v1 of the change: https://lkml.org/lkml/2016/3/6/202
>

this is a trivial fix of a potential NULL pointer dereference,
do you have any review comments?

> drivers/misc/sram.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index 69cdabe..f84b53d 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -364,8 +364,8 @@ static int sram_probe(struct platform_device *pdev)
> sram->virt_base = devm_ioremap(sram->dev, res->start, size);
> else
> sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
> - if (IS_ERR(sram->virt_base))
> - return PTR_ERR(sram->virt_base);
> + if (!sram->virt_base)
> + return -ENOMEM;
>
> sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
> NUMA_NO_NODE, NULL);
>

--
With best wishes,
Vladimir