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

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Date:   Sat, 19 Nov 2016 22:15:04 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Subhash Jadavani <subhashj@...eaurora.org>
Cc:     Vinayak Holikatti <vinholikatti@...il.com>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Yaniv Gardi <ygardi@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-scsi-owner@...r.kernel.org
Subject: Re: [PATCH] ufs: qcom: Properly clear hba priv on failure

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@...aro.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