On Fri, 27 Dec 2024 20:56:21 -0800 > syzbot has found a reproducer for the following issue on: > > HEAD commit: 8155b4ef3466 Add linux-next specific files for 20241220 > git tree: linux-next > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1652fadf980000 #syz test --- x/mm/filemap.c +++ y/mm/filemap.c @@ -3636,6 +3636,10 @@ static vm_fault_t filemap_map_folio_rang continue; skip: if (count) { + for (unsigned int i = 0; i < count; i++) { + if (page_folio(page + i) != folio) + goto out; + } set_pte_range(vmf, folio, page, count, addr); *rss += count; folio_ref_add(folio, count); @@ -3658,6 +3662,7 @@ skip: ret = VM_FAULT_NOPAGE; } +out: vmf->pte = old_ptep; return ret; @@ -3702,7 +3707,7 @@ vm_fault_t filemap_map_pages(struct vm_f struct file *file = vma->vm_file; struct address_space *mapping = file->f_mapping; pgoff_t file_end, last_pgoff = start_pgoff; - unsigned long addr; + unsigned long addr, pmd_end; XA_STATE(xas, &mapping->i_pages, start_pgoff); struct folio *folio; vm_fault_t ret = 0; @@ -3731,6 +3736,12 @@ vm_fault_t filemap_map_pages(struct vm_f if (end_pgoff > file_end) end_pgoff = file_end; + /* make vmf->pte[x] valid */ + pmd_end = ALIGN(addr, PMD_SIZE); + pmd_end = (pmd_end - addr) >> PAGE_SHIFT; + if (end_pgoff - start_pgoff > pmd_end) + end_pgoff = start_pgoff + pmd_end; + folio_type = mm_counter_file(folio); do { unsigned long end; --
