Hello Hugh Dickins,
The patch 0d940a9b270b: "mm/pgtable: allow pte_offset_map[_lock]() to
fail" from Jun 8, 2023, leads to the following Smatch static checker
warning:
mm/userfaultfd.c:321 mfill_atomic_pte_poison()
error: uninitialized symbol 'ptl'.
mm/userfaultfd.c
292 static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
293 struct vm_area_struct *dst_vma,
294 unsigned long dst_addr,
295 uffd_flags_t flags)
296 {
297 int ret;
298 struct mm_struct *dst_mm = dst_vma->vm_mm;
299 pte_t _dst_pte, *dst_pte;
300 spinlock_t *ptl;
301
302 _dst_pte = make_pte_marker(PTE_MARKER_POISONED);
303 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
^^^^
The __pte_offset_map_lock() function does not initialize ptl if it
returns NULL.
304
305 if (mfill_file_over_size(dst_vma, dst_addr)) {
306 ret = -EFAULT;
307 goto out_unlock;
308 }
309
310 ret = -EEXIST;
311 /* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */
312 if (!pte_none(*dst_pte))
313 goto out_unlock;
314
315 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
316
317 /* No need to invalidate - it was non-present before */
318 update_mmu_cache(dst_vma, dst_addr, dst_pte);
319 ret = 0;
320 out_unlock:
--> 321 pte_unmap_unlock(dst_pte, ptl);
322 return ret;
323 }
regards,
dan carpenter
