On 2/23/2021 12:45 PM, Alex Williamson wrote: > On Tue, 23 Feb 2021 08:56:36 -0500 > Steven Sistare <steven.sistare@xxxxxxxxxx> wrote: > >> On 2/22/2021 6:17 PM, Alex Williamson wrote: >>> On Mon, 22 Feb 2021 15:51:45 -0700 >>> Alex Williamson <alex.williamson@xxxxxxxxxx> wrote: >>> >>>> On Mon, 22 Feb 2021 17:10:43 +0300 >>>> Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: >>>> >>>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master >>>>> head: 37dfbfbdca66834bc0f64ec9b35e09ac6c8898da >>>>> commit: 0f53afa12baec8c00f5d1d6afb49325ada105253 [6931/12022] vfio/type1: unmap cleanup >>>> >>>> It's always the patches that claim no functional change... ;) >>>> >>>>> config: i386-randconfig-m021-20210222 (attached as .config) >>>>> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 >>>>> >>>>> If you fix the issue, kindly add following tag as appropriate >>>>> Reported-by: kernel test robot <lkp@xxxxxxxxx> >>>>> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> >>>>> >>>>> New smatch warnings: >>>>> drivers/vfio/vfio_iommu_type1.c:1093 vfio_dma_do_unmap() warn: impossible condition '(size > (~0)) => (0-u32max > u32max)' >>>>> >>>>> vim +1093 drivers/vfio/vfio_iommu_type1.c >>>>> >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1071 static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1072 struct vfio_iommu_type1_dma_unmap *unmap, >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1073 struct vfio_bitmap *bitmap) >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1074 { >>>>> c086de818dd81c Kirti Wankhede 2016-11-17 1075 struct vfio_dma *dma, *dma_last = NULL; >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1076 size_t unmapped = 0, pgsize; >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 1077 int ret = -EINVAL, retries = 0; >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1078 unsigned long pgshift; >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 1079 dma_addr_t iova = unmap->iova; >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 1080 unsigned long size = unmap->size; >>>>> ^^^^^^^^^^^^^^^^^^ >>>>> >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1081 >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1082 mutex_lock(&iommu->lock); >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1083 >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1084 pgshift = __ffs(iommu->pgsize_bitmap); >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1085 pgsize = (size_t)1 << pgshift; >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1086 >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 1087 if (iova & (pgsize - 1)) >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1088 goto unlock; >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1089 >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 1090 if (!size || size & (pgsize - 1)) >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1091 goto unlock; >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1092 >>>>> 0f53afa12baec8 Steve Sistare 2021-01-29 @1093 if (iova + size - 1 < iova || size > SIZE_MAX) >>>>> >>>>> size is unsigned long and SIZE_MAX is ULONG_MAX so "size > SIZE_MAX" >>>>> does not make sense. >>>> >>>> I think it made sense before the above commit, where unmap->size is a >>>> __u64 and a user could provide a value that exceeds SIZE_MAX on ILP32. >>>> Seems like the fix is probably to use a size_t for the local variable >>>> and restore this test to compare (unmap->size > SIZE_MAX). Steve? >>> >>> Actually it seems like VFIO_DMA_UNMAP_FLAG_ALL doesn't work when >>> PHYS_ADDR_MAX != SIZE_MAX (ex. x86 PAE - I think). >> >> It seems like PAE causes problems even before VFIO_DMA_UNMAP_FLAG_ALL. > > This wouldn't surprise me, I don't know of any actual non-64bit users > and pure 32bit support was only lightly validated ages ago. > >> In the previous vfio_dma_do_unmap code, the u64 unmap->size would be >> truncated when passed to vfio_find_dma. > > We would have failed with -EINVAL before we get there due to this > SIZE_MAX test. I think the existing (previous) PAE interface is at > least self consistent; I see the mapping path also attempts to check > that casting map->size as size_t still matches the original value. Good point, and it also checks for vaddr and iova overflow and wrap: vfio_dma_do_map() if (map->size != size || map->vaddr != vaddr || map->iova != iova) return -EINVAL; if (iova + size - 1 < iova || vaddr + size - 1 < vaddr) { ret = -EINVAL; With that, I don't see a problem with PAE, for unmap-all or otherwise. We just need "u64 size" in vfio_dma_do_unmap to avoid the smatch warning. - Steve >> For unmap, these fixes should suffice, and I would rather do this than >> disable the unmap-all flag for a corner case: >> >> vfio_dma_do_unmap() >> size_t unmapped = 0; >> unsigned long size = unmap->size; >> ==> >> u64 unmapped = 0; >> u64 size = unmap->size; >> >> static struct rb_node *vfio_find_dma_first_node( >> struct vfio_iommu *iommu, dma_addr_t start, size_t size) >> ==> >> static struct rb_node *vfio_find_dma_first_node( >> struct vfio_iommu *iommu, dma_addr_t start, u64 size) >> >> And maybe use dma_addr_t instead of u64 in the above (which is 64 bits for >> CONFIG_X86_PAE). >> >> However, there are other places in the existing code that need tweaking >> to be safe for PAE, the vfio_find_dma() size arg for one. > > Yes, it looks like the IOMMU aperture checking using vfio_find_dma() > could have issues where dma_addr_t > size_t. Do you want to propose a > patch? Thanks, > > Alex > >>> I can't say I'm >>> really interested in adding complexity to make it work in such a case >>> either. Maybe we can just not expose it, ex: >>> >>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>> index ed03f3fcb07e..6b69a74b3db0 100644 >>> --- a/drivers/vfio/vfio_iommu_type1.c >>> +++ b/drivers/vfio/vfio_iommu_type1.c >>> @@ -1207,7 +1207,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >>> int ret = -EINVAL, retries = 0; >>> unsigned long pgshift; >>> dma_addr_t iova = unmap->iova; >>> - unsigned long size = unmap->size; >>> + size_t size = unmap->size; >>> bool unmap_all = unmap->flags & VFIO_DMA_UNMAP_FLAG_ALL; >>> bool invalidate_vaddr = unmap->flags & VFIO_DMA_UNMAP_FLAG_VADDR; >>> struct rb_node *n, *first_n; >>> @@ -1228,7 +1228,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, >>> goto unlock; >>> } >>> >>> - if (iova + size - 1 < iova || size > SIZE_MAX) >>> + if (iova + size - 1 < iova || unmap->size > SIZE_MAX) >>> goto unlock; >>> >>> /* When dirty tracking is enabled, allow only min supported pgsize */ >>> @@ -2657,9 +2657,10 @@ static int vfio_iommu_type1_check_extension(struct vfio_iommu *iommu, >>> case VFIO_TYPE1_IOMMU: >>> case VFIO_TYPE1v2_IOMMU: >>> case VFIO_TYPE1_NESTING_IOMMU: >>> - case VFIO_UNMAP_ALL: >>> case VFIO_UPDATE_VADDR: >>> return 1; >>> + case VFIO_UNMAP_ALL: >>> + return PHYS_ADDR_MAX == SIZE_MAX ? 1 : 0; >>> case VFIO_DMA_CC_IOMMU: >>> if (!iommu) >>> return 0; >>> @@ -2868,6 +2869,10 @@ static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu, >>> VFIO_DMA_UNMAP_FLAG_VADDR))) >>> return -EINVAL; >>> >>> + if ((PHYS_ADDR_MAX != SIZE_MAX) && >>> + (unmap.flags & VFIO_DMA_UNMAP_FLAG_ALL)) >>> + return -EINVAL; >>> + >>> if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) { >>> unsigned long pgshift; >>> >>> >>> >>> >>> >>>>> Is the " - 1" intentional on the other overflow check? As in it's okay >>>>> to wrap around to zero but not further than that? Sometimes this is >>>>> intentional but it requires more subsystem expertise than I possess. >>>> >>>> Yes, since we're dealing with a start + length we need to account for >>>> the -1 in the end value, otherwise the user could never unmap the last >>>> page of the address space. Thanks for the report! >>>> >>>> Alex >>>> >>>>> cade075f265b25 Kirti Wankhede 2020-05-29 1094 goto unlock; >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1095 >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1096 /* When dirty tracking is enabled, allow only min supported pgsize */ >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1097 if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1098 (!iommu->dirty_page_tracking || (bitmap->pgsize != pgsize))) { >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1099 goto unlock; >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1100 } >>>>> 73fa0d10d077d9 Alex Williamson 2012-07-31 1101 >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1102 WARN_ON((pgsize - 1) & PAGE_MASK); >>>>> 331e33d2960c82 Kirti Wankhede 2020-05-29 1103 again: >>>>> 1ef3e2bc04223f Alex Williamson 2014-02-26 1104 /* >>>>> >>>>> --- >>>>> 0-DAY CI Kernel Test Service, Intel Corporation >>>>> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx >>>> >>> >> >
