From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ralph Campbell Subject: [PATCH 1/2] mm/hmm: hmm_range_fault() NULL pointer bug Date: Fri, 23 Aug 2019 15:17:52 -0700 Message-ID: <20190823221753.2514-2-rcampbell@nvidia.com> References: <20190823221753.2514-1-rcampbell@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20190823221753.2514-1-rcampbell@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Jason Gunthorpe , Andrew Morton , Christoph Hellwig , Ralph Campbell List-Id: amd-gfx.lists.freedesktop.org Although hmm_range_fault() calls find_vma() to make sure that a vma exists before calling walk_page_range(), hmm_vma_walk_hole() can still be called with walk->vma =3D=3D NULL if the start and end address are not contained within the vma range. hmm_range_fault() /* calls find_vma() but no range check */ walk_page_range() /* calls find_vma(), sets walk->vma =3D NULL */ __walk_page_range() walk_pgd_range() walk_p4d_range() walk_pud_range() hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(vma=3D0) Signed-off-by: Ralph Campbell --- mm/hmm.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index fc05c8fe78b4..29371485fe94 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -229,6 +229,9 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsig= ned long addr, struct vm_area_struct *vma =3D walk->vma; vm_fault_t ret; =20 + if (!vma) + goto err; + if (hmm_vma_walk->flags & HMM_FAULT_ALLOW_RETRY) flags |=3D FAULT_FLAG_ALLOW_RETRY; if (write_fault) @@ -239,12 +242,14 @@ static int hmm_vma_do_fault(struct mm_walk *walk, uns= igned long addr, /* Note, handle_mm_fault did up_read(&mm->mmap_sem)) */ return -EAGAIN; } - if (ret & VM_FAULT_ERROR) { - *pfn =3D range->values[HMM_PFN_ERROR]; - return -EFAULT; - } + if (ret & VM_FAULT_ERROR) + goto err; =20 return -EBUSY; + +err: + *pfn =3D range->values[HMM_PFN_ERROR]; + return -EFAULT; } =20 static int hmm_pfns_bad(unsigned long addr, --=20 2.20.1