From: Ralph Campbell <rcampbell@nvidia.com> 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, "Jérôme Glisse" <jglisse@redhat.com>, "Jason Gunthorpe" <jgg@mellanox.com>, "Andrew Morton" <akpm@linux-foundation.org>, "Christoph Hellwig" <hch@lst.de>, "Ralph Campbell" <rcampbell@nvidia.com> Subject: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Date: Fri, 23 Aug 2019 15:17:53 -0700 [thread overview] Message-ID: <20190823221753.2514-3-rcampbell@nvidia.com> (raw) In-Reply-To: <20190823221753.2514-1-rcampbell@nvidia.com> Normally, callers to handle_mm_fault() are supposed to check the vma->vm_flags first. hmm_range_fault() checks for VM_READ but doesn't check for VM_WRITE if the caller requests a page to be faulted in with write permission (via the hmm_range.pfns[] value). If the vma is write protected, this can result in an infinite loop: hmm_range_fault() walk_page_range() ... hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(FAULT_FLAG_WRITE) /* returns VM_FAULT_WRITE */ /* returns -EBUSY */ /* returns -EBUSY */ /* returns -EBUSY */ /* loops on -EBUSY and range->valid */ Prevent this by checking for vma->vm_flags & VM_WRITE before calling handle_mm_fault(). Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> --- mm/hmm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index 29371485fe94..4882b83aeccb 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end, hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) + return -EPERM; + for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = range->values[HMM_PFN_NONE]; if (fault || write_fault) { -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Ralph Campbell <rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> To: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org Cc: "Ralph Campbell" <rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, "Jérôme Glisse" <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "Jason Gunthorpe" <jgg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, "Andrew Morton" <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "Christoph Hellwig" <hch-jcswGhMUV9g@public.gmane.org> Subject: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Date: Fri, 23 Aug 2019 15:17:53 -0700 [thread overview] Message-ID: <20190823221753.2514-3-rcampbell@nvidia.com> (raw) In-Reply-To: <20190823221753.2514-1-rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Normally, callers to handle_mm_fault() are supposed to check the vma->vm_flags first. hmm_range_fault() checks for VM_READ but doesn't check for VM_WRITE if the caller requests a page to be faulted in with write permission (via the hmm_range.pfns[] value). If the vma is write protected, this can result in an infinite loop: hmm_range_fault() walk_page_range() ... hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(FAULT_FLAG_WRITE) /* returns VM_FAULT_WRITE */ /* returns -EBUSY */ /* returns -EBUSY */ /* returns -EBUSY */ /* loops on -EBUSY and range->valid */ Prevent this by checking for vma->vm_flags & VM_WRITE before calling handle_mm_fault(). Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> --- mm/hmm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index 29371485fe94..4882b83aeccb 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end, hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) + return -EPERM; + for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = range->values[HMM_PFN_NONE]; if (fault || write_fault) { -- 2.20.1 _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
next prev parent reply other threads:[~2019-08-23 22:18 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-23 22:17 [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Ralph Campbell 2019-08-23 22:17 ` Ralph Campbell 2019-08-23 22:17 ` [PATCH 1/2] mm/hmm: hmm_range_fault() NULL pointer bug Ralph Campbell 2019-08-23 22:17 ` Ralph Campbell 2019-08-24 22:37 ` Christoph Hellwig 2019-08-24 22:37 ` Christoph Hellwig 2019-08-26 18:02 ` Ralph Campbell 2019-08-26 18:02 ` Ralph Campbell 2019-08-26 18:09 ` Jason Gunthorpe 2019-08-26 18:21 ` Ralph Campbell 2019-08-23 22:17 ` Ralph Campbell [this message] 2019-08-23 22:17 ` [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Ralph Campbell 2019-08-24 22:39 ` Christoph Hellwig 2019-08-27 18:41 ` Jason Gunthorpe 2019-08-27 20:16 ` Ralph Campbell 2019-08-27 20:16 ` Ralph Campbell 2019-08-27 22:22 ` Jason Gunthorpe 2019-08-27 22:48 ` [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Jason Gunthorpe
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