linux-kernel - [PATCH 4.2 014/110] iommu/amd: Fix BUG when faulting a PROT

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Message-Id: <20151106191703.927903510@linuxfoundation.org>
Date:	Fri,  6 Nov 2015 11:18:21 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Jay Cornwall <jay@...rnwall.me>,
	Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 4.2 014/110] iommu/amd: Fix BUG when faulting a PROT_NONE VMA

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jay Cornwall <jay@...rnwall.me>

commit d14f6fced5f9360edca5a1325ddb7077aab1203b upstream.

handle_mm_fault indirectly triggers a BUG in do_numa_page
when given a VMA without read/write/execute access. Check
this condition in do_fault.

do_fault -> handle_mm_fault -> handle_pte_fault -> do_numa_page

  mm/memory.c
  3147  static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
  ....
  3159  /* A PROT_NONE fault should not end up here */
  3160  BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));

Signed-off-by: Jay Cornwall <jay@...rnwall.me>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iommu/amd_iommu_v2.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -516,6 +516,13 @@ static void do_fault(struct work_struct
 		goto out;
 	}
 
+	if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) {
+		/* handle_mm_fault would BUG_ON() */
+		up_read(&mm->mmap_sem);
+		handle_fault_error(fault);
+		goto out;
+	}
+
 	ret = handle_mm_fault(mm, vma, address, write);
 	if (ret & VM_FAULT_ERROR) {
 		/* failed to service fault */


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