On Mon, Jul 16, 2018 at 06:33:52PM +0300, Mikko Perttunen wrote:
>
>
> On 07/16/2018 05:55 PM, LABBE Corentin wrote:
> > On Mon, Jul 16, 2018 at 04:11:44PM +0300, Mikko Perttunen wrote:
> >> Hello,
> >>
> >> the recently applied "ata: ahci_platform: convert kcalloc to
> >> devm_kcalloc" seems to be causing boot failures on Tegra124 Jetson TK1.
> >> The patch is as follows:
> >>
> >> diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> >> index be9f54423a9b..fe8939e161ea 100644
> >> --- a/drivers/ata/libahci_platform.c
> >> +++ b/drivers/ata/libahci_platform.c
> >> @@ -271,8 +271,6 @@ static void ahci_platform_put_resources(struct
> >> device *dev, void *res)
> >> for (c = 0; c < hpriv->nports; c++)
> >> if (hpriv->target_pwrs && hpriv->target_pwrs[c])
> >> regulator_put(hpriv->target_pwrs[c]);
> >> -
> >> - kfree(hpriv->target_pwrs);
> >> }
> >>
> >> static int ahci_platform_get_phy(struct ahci_host_priv *hpriv, u32 port,
> >> @@ -408,7 +406,7 @@ struct ahci_host_priv
> >> *ahci_platform_get_resources(struct platform_device *pdev)
> >> rc = -ENOMEM;
> >> goto err_out;
> >> }
> >> - hpriv->target_pwrs = kcalloc(hpriv->nports,
> >> sizeof(*hpriv->target_pwrs), GFP_KERNEL);
> >> + hpriv->target_pwrs = devm_kcalloc(dev, hpriv->nports,
> >> sizeof(*hpriv->target_pwrs), GFP_KERNEL);
> >> if (!hpriv->target_pwrs) {
> >> rc = -ENOMEM;
> >> goto err_out;
> >>
> >> However, this is not valid, as it will cause hpriv->target_pwrs to be
> >> freed before ahci_platform_put_resources is called. With the older code,
> >> the free happened intentionally only after the regulator_put calls were
> >> done.
> >>
> >
> > Hello
> >
> > I am surprised, since I have tested all my AHCI patch on a Tegra124 Jetson TK1.
> > Could you print the boot crash ?
>
> I don't have the crash log in front of me now (can get it to you
> tomorrow), but basically it was ahci_platform_put_resources calling
> eventually _regulator_put which was dereferencing 0x6b6b6bbf, quite
> clearly an offset of 0x6b6b6b6b which is the use-after-free poison.
>
> It actually only happens on tegra_defconfig -- I assume there's some
> different dependency situation that doesn't happen on
> multi_v7_defconfig, that causes ahci-tegra to defer probe, causing the
> error path to be triggered.
>
I have just checked on kernelci.org, and see what you said.
And yes it was the PHY defer which cause this, and explains why I didnt hit the case (I was not using defconfig).
I will send a commit that revert the change add add a warning on why it must remains a simple kcalloc.
Thanks
Regards
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