The return value of hga_card_detect() is not properly handled causing
the probe to succeed even though hga_card_detect() failed. Since probe
succeeds, hgafb_open() can be called which will end up operating on an
unmapped hga_vram. This results in an out-of-bounds access as reported
by kernel test robot [1].
To fix this, correctly detect failure of hga_card_detect() by checking
for a non-zero error code.
[1]: https://lore.kernel.org/lkml/20210516150019.GB25903@xsang-OptiPlex-9020/
Reported-by: kernel test robot <[email protected]>
Fixes: dc13cac4862c ("video: hgafb: fix potential NULL pointer dereference")
Cc: stable <[email protected]>
Signed-off-by: Anirudh Rayabharam <[email protected]>
---
drivers/video/fbdev/hgafb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/hgafb.c b/drivers/video/fbdev/hgafb.c
index cc8e62ae93f6..bd3d07aa4f0e 100644
--- a/drivers/video/fbdev/hgafb.c
+++ b/drivers/video/fbdev/hgafb.c
@@ -558,7 +558,7 @@ static int hgafb_probe(struct platform_device *pdev)
int ret;
ret = hga_card_detect();
- if (!ret)
+ if (ret)
return ret;
printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
--
2.26.2
Hi,
On 5/16/21 4:27 PM, Anirudh Rayabharam wrote:
> The return value of hga_card_detect() is not properly handled causing
> the probe to succeed even though hga_card_detect() failed. Since probe
> succeeds, hgafb_open() can be called which will end up operating on an
> unmapped hga_vram. This results in an out-of-bounds access as reported
> by kernel test robot [1].
>
> To fix this, correctly detect failure of hga_card_detect() by checking
> for a non-zero error code.
>
> [1]: https://lore.kernel.org/lkml/20210516150019.GB25903@xsang-OptiPlex-9020/
>
> Reported-by: kernel test robot <[email protected]>
> Fixes: dc13cac4862c ("video: hgafb: fix potential NULL pointer dereference")
> Cc: stable <[email protected]>
> Signed-off-by: Anirudh Rayabharam <[email protected]>
> ---
> drivers/video/fbdev/hgafb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/hgafb.c b/drivers/video/fbdev/hgafb.c
> index cc8e62ae93f6..bd3d07aa4f0e 100644
> --- a/drivers/video/fbdev/hgafb.c
> +++ b/drivers/video/fbdev/hgafb.c
> @@ -558,7 +558,7 @@ static int hgafb_probe(struct platform_device *pdev)
> int ret;
>
> ret = hga_card_detect();
> - if (!ret)
> + if (ret)
> return ret;
>
> printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
>
In fact, this return isn't being properly handled. Thanks for fix it!
Reviewed-by: Igor Matheus Andrade Torrente <[email protected]>
On Mon, May 17, 2021 at 12:57:14AM +0530, Anirudh Rayabharam wrote:
> The return value of hga_card_detect() is not properly handled causing
> the probe to succeed even though hga_card_detect() failed. Since probe
> succeeds, hgafb_open() can be called which will end up operating on an
> unmapped hga_vram. This results in an out-of-bounds access as reported
> by kernel test robot [1].
>
> To fix this, correctly detect failure of hga_card_detect() by checking
> for a non-zero error code.
>
> [1]: https://lore.kernel.org/lkml/20210516150019.GB25903@xsang-OptiPlex-9020/
>
> Reported-by: kernel test robot <[email protected]>
> Fixes: dc13cac4862c ("video: hgafb: fix potential NULL pointer dereference")
Greg, this is one of the UMN fixes we did. So, do you want to take this
patch into your tree?
thanks!
- Anirudh.
> Cc: stable <[email protected]>
> Signed-off-by: Anirudh Rayabharam <[email protected]>
> ---
> drivers/video/fbdev/hgafb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/hgafb.c b/drivers/video/fbdev/hgafb.c
> index cc8e62ae93f6..bd3d07aa4f0e 100644
> --- a/drivers/video/fbdev/hgafb.c
> +++ b/drivers/video/fbdev/hgafb.c
> @@ -558,7 +558,7 @@ static int hgafb_probe(struct platform_device *pdev)
> int ret;
>
> ret = hga_card_detect();
> - if (!ret)
> + if (ret)
> return ret;
>
> printk(KERN_INFO "hgafb: %s with %ldK of memory detected.\n",
> --
> 2.26.2
>
On Thu, May 20, 2021 at 07:10:39PM +0530, Anirudh Rayabharam wrote:
> On Mon, May 17, 2021 at 12:57:14AM +0530, Anirudh Rayabharam wrote:
> > The return value of hga_card_detect() is not properly handled causing
> > the probe to succeed even though hga_card_detect() failed. Since probe
> > succeeds, hgafb_open() can be called which will end up operating on an
> > unmapped hga_vram. This results in an out-of-bounds access as reported
> > by kernel test robot [1].
> >
> > To fix this, correctly detect failure of hga_card_detect() by checking
> > for a non-zero error code.
> >
> > [1]: https://lore.kernel.org/lkml/20210516150019.GB25903@xsang-OptiPlex-9020/
> >
> > Reported-by: kernel test robot <[email protected]>
> > Fixes: dc13cac4862c ("video: hgafb: fix potential NULL pointer dereference")
>
> Greg, this is one of the UMN fixes we did. So, do you want to take this
> patch into your tree?
Yes, will queue it up in a few days after Linus takes the current pull
request I sent him for this.
thanks,
greg k-h