Hello David Woodhouse,
This is a semi-automatic email about new static checker warnings.
The patch 0b9252a34858: "iommu/vt-d: Implement page request handling"
from Oct 8, 2015, leads to the following Smatch complaint:
drivers/iommu/intel-svm.c:452 prq_event_thread()
error: we previously assumed 'svm' could be null (see line 412)
drivers/iommu/intel-svm.c
411 svm = idr_find(&iommu->pasid_idr, req->pasid);
412 if (!svm) {
The patch adds a NULL check here.
413 pr_err("%s: Page request for invalid
PASID %d: %08llx %08llx\n",
414 iommu->name, req->pasid,
((unsigned long long *)req)[0],
415 ((unsigned long long *)req)[1]);
416 mutex_unlock(&pasid_mutex);
417 goto inval_req;
418 }
419 /* Strictly speaking, we shouldn't need this.
It is forbidden
420 to unbind the PASID while there may still be
requests in
421 flight. But let's do it anyway. */
422 kref_get(&svm->kref);
423 mutex_unlock(&pasid_mutex);
424 }
425
426 result = QI_RESP_FAILURE;
427 down_read(&svm->mm->mmap_sem);
428 vma = find_extend_vma(svm->mm, address);
429 if (!vma || address < vma->vm_start)
430 goto hard_fault;
431
432 ret = handle_mm_fault(svm->mm, vma, address,
433 req->wr_req ? FAULT_FLAG_WRITE :
0);
434 if (ret & VM_FAULT_ERROR)
435 goto hard_fault;
436
437 result = QI_RESP_SUCCESS;
438 hard_fault:
439 up_read(&svm->mm->mmap_sem);
440 inval_req:
441 /* Accounting for major/minor faults? */
442
443 if (req->lpig) {
Perhaps this check ensures that "svm" is not NULL but I don't know the
code well enough to say.
444 /* Page Group Response */
445 resp.low = QI_PGRP_PASID(req->pasid) |
446 QI_PGRP_DID((req->bus << 8) |
req->devfn) |
447 QI_PGRP_PASID_P(req->pasid_present) |
448 QI_PGRP_RESP_TYPE;
449 resp.high = QI_PGRP_IDX(req->prg_index) |
450 QI_PGRP_PRIV(req->private) |
QI_PGRP_RESP_CODE(result);
451
452 qi_submit_sync(&resp, svm->iommu);
^^^^^^^^^^
The patch introduces a NULL dereference here.
453 } else if (req->srr) {
454 /* Page Stream Response */
regards,
dan carpenter
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