[PATCH] ufs: qcom: Properly clear hba priv on failure

[PATCH] ufs: qcom: Properly clear hba priv on failure

[Bjorn Andersson]

In the case where we fail to acquire the phy the hba priv will be set
already, so during cleanup ufs_qcom_setup_clocks() will dereference the
now free, but still "valid looking" pointer "host".

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
 drivers/scsi/ufs/ufs-qcom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index d345434b084f..7bd88ffee47a 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -1197,7 +1197,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	if (IS_ERR(host->generic_phy)) {
 		err = PTR_ERR(host->generic_phy);
 		dev_err(dev, "%s: PHY get failed %d\n", __func__, err);
-		goto out;
+		goto out_host_free;
 	}
 
 	err = ufs_qcom_bus_register(host);
-- 
2.5.0

Re: [PATCH] ufs: qcom: Properly clear hba priv on failure

[Subhash Jadavani]

On 2016-11-18 12:55, Bjorn Andersson wrote:
> In the case where we fail to acquire the phy the hba priv will be set
> already, so during cleanup ufs_qcom_setup_clocks() will dereference the
> now free, but still "valid looking" pointer "host".

host (ufs_qcom_host) was allocated with devm_kzalloc() so i am not sure 
why it would be freed up before probe() returns failure.

> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>  drivers/scsi/ufs/ufs-qcom.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index d345434b084f..7bd88ffee47a 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -1197,7 +1197,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>  	if (IS_ERR(host->generic_phy)) {
>  		err = PTR_ERR(host->generic_phy);
>  		dev_err(dev, "%s: PHY get failed %d\n", __func__, err);
> -		goto out;
> +		goto out_host_free;
>  	}
> 
>  	err = ufs_qcom_bus_register(host);

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] ufs: qcom: Properly clear hba priv on failure

[Bjorn Andersson]

On Sat 19 Nov 12:30 PST 2016, Subhash Jadavani wrote:

> On 2016-11-18 12:55, Bjorn Andersson wrote:
> >In the case where we fail to acquire the phy the hba priv will be set
> >already, so during cleanup ufs_qcom_setup_clocks() will dereference the
> >now free, but still "valid looking" pointer "host".
> 
> host (ufs_qcom_host) was allocated with devm_kzalloc() so i am not sure why
> it would be freed up before probe() returns failure.
> 

Sorry, I missed the fact that the devm_kfree() was dropped, the actual
problem still remains, although it no longer results in a panic.

As ufs_qcom_init() returns from not having found the phy it the variant
data will be a zero-initialized object.  The error path of
ufshcd_hba_init() will then take us through ufs_qcom_setup_clocks(),
which will pass the check for a NULL variant data and use the
uninitialized host object.

I can update the commit message to reflect the new state of things.

Regards,
Bjorn

> >Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> >---
> > drivers/scsi/ufs/ufs-qcom.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> >index d345434b084f..7bd88ffee47a 100644
> >--- a/drivers/scsi/ufs/ufs-qcom.c
> >+++ b/drivers/scsi/ufs/ufs-qcom.c
> >@@ -1197,7 +1197,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> > 	if (IS_ERR(host->generic_phy)) {
> > 		err = PTR_ERR(host->generic_phy);
> > 		dev_err(dev, "%s: PHY get failed %d\n", __func__, err);
> >-		goto out;
> >+		goto out_host_free;
> > 	}
> >
> > 	err = ufs_qcom_bus_register(host);
> 
> -- 
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

Re: [PATCH] ufs: qcom: Properly clear hba priv on failure

[Subhash Jadavani]

On 2016-11-19 22:15, Bjorn Andersson wrote:
> On Sat 19 Nov 12:30 PST 2016, Subhash Jadavani wrote:
> 
>> On 2016-11-18 12:55, Bjorn Andersson wrote:
>> >In the case where we fail to acquire the phy the hba priv will be set
>> >already, so during cleanup ufs_qcom_setup_clocks() will dereference the
>> >now free, but still "valid looking" pointer "host".
>> 
>> host (ufs_qcom_host) was allocated with devm_kzalloc() so i am not 
>> sure why
>> it would be freed up before probe() returns failure.
>> 
> 
> Sorry, I missed the fact that the devm_kfree() was dropped, the actual
> problem still remains, although it no longer results in a panic.

Agreed.

> 
> As ufs_qcom_init() returns from not having found the phy it the variant
> data will be a zero-initialized object.  The error path of
> ufshcd_hba_init() will then take us through ufs_qcom_setup_clocks(),
> which will pass the check for a NULL variant data and use the
> uninitialized host object.

Yes, Make sense.

> 
> I can update the commit message to reflect the new state of things.

Your new patch set looks good, will add my ack.

> 
> Regards,
> Bjorn
> 
>> >Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
>> >---
>> > drivers/scsi/ufs/ufs-qcom.c | 2 +-
>> > 1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> >diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
>> >index d345434b084f..7bd88ffee47a 100644
>> >--- a/drivers/scsi/ufs/ufs-qcom.c
>> >+++ b/drivers/scsi/ufs/ufs-qcom.c
>> >@@ -1197,7 +1197,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>> > 	if (IS_ERR(host->generic_phy)) {
>> > 		err = PTR_ERR(host->generic_phy);
>> > 		dev_err(dev, "%s: PHY get failed %d\n", __func__, err);
>> >-		goto out;
>> >+		goto out_host_free;
>> > 	}
>> >
>> > 	err = ufs_qcom_bus_register(host);
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> a Linux Foundation Collaborative Project
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-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project