Messages in this thread | | | Subject | Re: [PATCH 1/1] iommu/vtd: Fix NULL pointer dereference in prq_event_thread() | From | Lu Baolu <> | Date | Mon, 5 Nov 2018 13:44:44 +0800 |
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Hi Yi,
On 11/5/18 1:21 PM, Liu, Yi L wrote: > Hi Baolu, > >> From: iommu-bounces@lists.linux-foundation.org [mailto:iommu- >> bounces@lists.linux-foundation.org] On Behalf Of Lu Baolu >> Sent: Monday, November 5, 2018 10:19 AM >> To: Joerg Roedel <joro@8bytes.org>; David Woodhouse <dwmw2@infradead.org> >> Cc: Raj, Ashok <ashok.raj@intel.com>; linux-kernel@vger.kernel.org; >> iommu@lists.linux-foundation.org >> Subject: [PATCH 1/1] iommu/vtd: Fix NULL pointer dereference in prq_event_thread() >> >> When handling page request without pasid event, go to "no_pasid" >> branch instead of "bad_req". Otherwise, a NULL pointer deference will happen there. >> >> Cc: Ashok Raj <ashok.raj@intel.com> >> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Cc: Sohil Mehta <sohil.mehta@intel.com> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> --- >> drivers/iommu/intel-svm.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c index >> db301efe126d..887150907526 100644 >> --- a/drivers/iommu/intel-svm.c >> +++ b/drivers/iommu/intel-svm.c >> @@ -595,7 +595,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> pr_err("%s: Page request without PASID: %08llx %08llx\n", >> iommu->name, ((unsigned long long *)req)[0], >> ((unsigned long long *)req)[1]); >> - goto bad_req; >> + goto no_pasid; >> } >> >> if (!svm || svm->pasid != req->pasid) { >> -- > > I'm afraid it is still necessary to goto "bad_req". The following code behind > "bad_req" will trigger fault_cb registered by in-kernel drivers. It is reasonable > that PRQ without PASID can be handled by such callbacks. So I would suggest > to keep the existing logic.
A page fault without a pasid is triggered by a DMA transfer without PASID. It doesn't relate to the SVM functionality hence there's no @svm or @sdev related to it. It's unnecessary to report it to the drivers as far as I can see.
Best regards, Lu Baolu
> > if (sdev && sdev->ops && sdev->ops->fault_cb) { > int rwxp = (req->rd_req << 3) | (req->wr_req << 2) | > (req->exe_req << 1) | (req->priv_req); > sdev->ops->fault_cb(sdev->dev, req->pasid, req->addr, req->private, rwxp, result); > } > > Thanks, > Yi Liu >
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