diff options
| author | Jason Gunthorpe <jgg@nvidia.com> | 2025-07-17 11:46:55 -0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2025-07-17 11:46:55 -0300 |
| commit | b42497e3c0e74db061eafad41c0cd7243c46436b (patch) | |
| tree | b01a120f6428a55140d6debb8055d6a5b9f413bf | |
| parent | 601b1d0d9395c711383452bd0d47037afbbb4bcf (diff) | |
iommufd: Prevent ALIGN() overflow
When allocating IOVA the candidate range gets aligned to the target
alignment. If the range is close to ULONG_MAX then the ALIGN() can
wrap resulting in a corrupted iova.
Open code the ALIGN() using get_add_overflow() to prevent this.
This simplifies the checks as we don't need to check for length earlier
either.
Consolidate the two copies of this code under a single helper.
This bug would allow userspace to create a mapping that overlaps with some
other mapping or a reserved range.
Cc: stable@vger.kernel.org
Fixes: 51fe6141f0f6 ("iommufd: Data structure to provide IOVA to PFN mapping")
Reported-by: syzbot+c2f65e2801743ca64e08@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/685af644.a00a0220.2e5631.0094.GAE@google.com
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Link: https://patch.msgid.link/all/1-v1-7b4a16fc390b+10f4-iommufd_alloc_overflow_jgg@nvidia.com/
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
| -rw-r--r-- | drivers/iommu/iommufd/io_pagetable.c | 41 |
1 files changed, 25 insertions, 16 deletions
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index abf4aadca96c..c0360c450880 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -70,36 +70,45 @@ struct iopt_area *iopt_area_contig_next(struct iopt_area_contig_iter *iter) return iter->area; } -static bool __alloc_iova_check_hole(struct interval_tree_double_span_iter *span, - unsigned long length, - unsigned long iova_alignment, - unsigned long page_offset) +static bool __alloc_iova_check_range(unsigned long *start, unsigned long last, + unsigned long length, + unsigned long iova_alignment, + unsigned long page_offset) { - if (span->is_used || span->last_hole - span->start_hole < length - 1) + unsigned long aligned_start; + + /* ALIGN_UP() */ + if (check_add_overflow(*start, iova_alignment - 1, &aligned_start)) return false; + aligned_start &= ~(iova_alignment - 1); + aligned_start |= page_offset; - span->start_hole = ALIGN(span->start_hole, iova_alignment) | - page_offset; - if (span->start_hole > span->last_hole || - span->last_hole - span->start_hole < length - 1) + if (aligned_start >= last || last - aligned_start < length - 1) return false; + *start = aligned_start; return true; } -static bool __alloc_iova_check_used(struct interval_tree_span_iter *span, +static bool __alloc_iova_check_hole(struct interval_tree_double_span_iter *span, unsigned long length, unsigned long iova_alignment, unsigned long page_offset) { - if (span->is_hole || span->last_used - span->start_used < length - 1) + if (span->is_used) return false; + return __alloc_iova_check_range(&span->start_hole, span->last_hole, + length, iova_alignment, page_offset); +} - span->start_used = ALIGN(span->start_used, iova_alignment) | - page_offset; - if (span->start_used > span->last_used || - span->last_used - span->start_used < length - 1) +static bool __alloc_iova_check_used(struct interval_tree_span_iter *span, + unsigned long length, + unsigned long iova_alignment, + unsigned long page_offset) +{ + if (span->is_hole) return false; - return true; + return __alloc_iova_check_range(&span->start_used, span->last_used, + length, iova_alignment, page_offset); } /* |