6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jason Gunthorpe jgg@nvidia.com
commit b42497e3c0e74db061eafad41c0cd7243c46436b upstream.
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_j... Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/iommufd/io_pagetable.c | 41 +++++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 16 deletions(-)
--- 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( 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); }
/*