{"id":"DEBIAN-CVE-2026-31648","details":"In the Linux kernel, the following vulnerability has been resolved:  mm: filemap: fix nr_pages calculation overflow in filemap_map_pages()  When running stress-ng on my Arm64 machine with v7.0-rc3 kernel, I encountered some very strange crash issues showing up as \"Bad page state\":  \" [  734.496287] BUG: Bad page state in process stress-ng-env  pfn:415735fb [  734.496427] page: refcount:0 mapcount:1 mapping:0000000000000000 index:0x4cf316 pfn:0x415735fb [  734.496434] flags: 0x57fffe000000800(owner_2|node=1|zone=2|lastcpupid=0x3ffff) [  734.496439] raw: 057fffe000000800 0000000000000000 dead000000000122 0000000000000000 [  734.496440] raw: 00000000004cf316 0000000000000000 0000000000000000 0000000000000000 [  734.496442] page dumped because: nonzero mapcount \"  After analyzing this page’s state, it is hard to understand why the mapcount is not 0 while the refcount is 0, since this page is not where the issue first occurred.  By enabling the CONFIG_DEBUG_VM config, I can reproduce the crash as well and captured the first warning where the issue appears:  \" [  734.469226] page: refcount:33 mapcount:0 mapping:00000000bef2d187 index:0x81a0 pfn:0x415735c0 [  734.469304] head: order:5 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 [  734.469315] memcg:ffff000807a8ec00 [  734.469320] aops:ext4_da_aops ino:100b6f dentry name(?):\"stress-ng-mmaptorture-9397-0-2736200540\" [  734.469335] flags: 0x57fffe400000069(locked|uptodate|lru|head|node=1|zone=2|lastcpupid=0x3ffff) ...... [  734.469364] page dumped because: VM_WARN_ON_FOLIO((_Generic((page + nr_pages - 1), const struct page *: (const struct folio *)_compound_head(page + nr_pages - 1), struct page *: (struct folio *)_compound_head(page + nr_pages - 1))) != folio) [  734.469390] ------------[ cut here ]------------ [  734.469393] WARNING: ./include/linux/rmap.h:351 at folio_add_file_rmap_ptes+0x3b8/0x468, CPU#90: stress-ng-mlock/9430 [  734.469551]  folio_add_file_rmap_ptes+0x3b8/0x468 (P) [  734.469555]  set_pte_range+0xd8/0x2f8 [  734.469566]  filemap_map_folio_range+0x190/0x400 [  734.469579]  filemap_map_pages+0x348/0x638 [  734.469583]  do_fault_around+0x140/0x198 ...... [  734.469640]  el0t_64_sync+0x184/0x188 \"  The code that triggers the warning is: \"VM_WARN_ON_FOLIO(page_folio(page + nr_pages - 1) != folio, folio)\", which indicates that set_pte_range() tried to map beyond the large folio’s size.  By adding more debug information, I found that 'nr_pages' had overflowed in filemap_map_pages(), causing set_pte_range() to establish mappings for a range exceeding the folio size, potentially corrupting fields of pages that do not belong to this folio (e.g., page-\u003e_mapcount).  After above analysis, I think the possible race is as follows:  CPU 0                                                  CPU 1 filemap_map_pages()                                   ext4_setattr()    //get and lock folio with old inode-\u003ei_size    next_uptodate_folio()                                                            .......                                                           //shrink the inode-\u003ei_size                                                           i_size_write(inode, attr-\u003eia_size);     //calculate the end_pgoff with the new inode-\u003ei_size    file_end = DIV_ROUND_UP(i_size_read(mapping-\u003ehost), PAGE_SIZE) - 1;    end_pgoff = min(end_pgoff, file_end);     ......    //nr_pages can be overflowed, cause xas.xa_index \u003e end_pgoff    end = folio_next_index(folio) - 1;    nr_pages = min(end, end_pgoff) - xas.xa_index + 1;     ......    //map large folio    filemap_map_folio_range()                                                           ......                                                           //truncate folios                                                           truncate_pagecache(inode, inode-\u003ei_size);  To fix this issue, move the 'end_pgoff' calculation before next_uptodate_folio(), so the retrieved folio stays consistent with the file end to avoid  ---truncated---","modified":"2026-09-29T13:03:40.010348189Z","published":"2026-04-24T15:16:44.193Z","upstream":["CVE-2026-31648"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-31648"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.187-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1","6.10-1~exp1","6.10.1-1~exp1","6.10.11-1","6.10.11-1~bpo12+1","6.10.12-1","6.10.3-1","6.10.4-1","6.10.6-1","6.10.6-1~bpo12+1","6.10.7-1","6.10.9-1","6.11-1~exp1","6.11.10-1","6.11.10-1~bpo12+1","6.11.2-1","6.11.4-1","6.11.5-1","6.11.5-1~bpo12+1","6.11.6-1","6.11.7-1","6.11.9-1","6.11~rc4-1~exp1","6.11~rc5-1~exp1","6.12.10-1","6.12.100-1","6.12.101-1","6.12.105-1","6.12.107-1","6.12.11-1","6.12.11-1+alpha","6.12.11-1+alpha.1","6.12.111-1","6.12.12-1","6.12.12-1~bpo12+1","6.12.13-1","6.12.15-1","6.12.16-1","6.12.17-1","6.12.19-1","6.12.20-1","6.12.21-1","6.12.22-1","6.12.22-1~bpo12+1","6.12.25-1","6.12.27-1","6.12.27-1~bpo12+1","6.12.29-1","6.12.3-1","6.12.30-1","6.12.30-1~bpo12+1","6.12.31-1","6.12.32-1","6.12.32-1~bpo12+1","6.12.33-1","6.12.33-1~bpo12+1","6.12.35-1","6.12.35-1~bpo12+1","6.12.37-1","6.12.38-1","6.12.38-1~bpo12+1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.5-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.6-1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.8-1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.9-1","6.12.9-1+alpha","6.12.9-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.12~rc6-1~exp1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.10-1","6.18.12-1","6.18.12-1~bpo13+1","6.18.13-1","6.18.14-1","6.18.15-1","6.18.15-1~bpo13+1","6.18.2-1~exp1","6.18.3-1","6.18.5-1","6.18.5-1~bpo13+1","6.18.8-1","6.18.9-1","6.18.9-1~bpo13+1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1","6.19-1~exp1","6.19.10-1","6.19.10-1~bpo13+1","6.19.11-1","6.19.11-1~bpo13+1","6.19.12-1","6.19.13-1","6.19.13-1~bpo13+1","6.19.14-1","6.19.14-1~bpo13+1","6.19.2-1~exp1","6.19.3-1~exp1","6.19.4-1~exp1","6.19.5-1~exp1","6.19.6-1","6.19.6-2","6.19.6-2~bpo13+1","6.19.8-1","6.19.8-1~bpo13+1","6.19~rc4-1~exp1","6.19~rc5-1~exp1","6.19~rc6-1~exp1","6.19~rc7-1~exp1","6.19~rc8-1~exp1","6.3.1-1~exp1","6.3.11-1","6.3.2-1~exp1","6.3.4-1~exp1","6.3.5-1~exp1","6.3.7-1","6.3.7-1~bpo12+1","6.4.1-1~exp1","6.4.11-1","6.4.13-1","6.4.4-1","6.4.4-1~bpo12+1","6.4.4-2","6.4.4-3","6.4.4-3~bpo12+1","6.4~rc6-1~exp1","6.4~rc7-1~exp1","6.5.1-1~exp1","6.5.10-1","6.5.10-1~bpo12+1","6.5.13-1","6.5.3-1","6.5.3-1~bpo12+1","6.5.6-1","6.5.8-1","6.5~rc4-1~exp1","6.5~rc6-1~exp1","6.5~rc7-1~exp1","6.6.11-1","6.6.13-1","6.6.13-1~bpo12+1","6.6.15-1","6.6.15-2","6.6.3-1~exp1","6.6.4-1~exp1","6.6.7-1~exp1","6.6.8-1","6.6.9-1","6.7-1~exp1","6.7.1-1~exp1","6.7.12-1","6.7.12-1~bpo12+1","6.7.4-1~exp1","6.7.7-1","6.7.9-1","6.7.9-2","6.8.11-1","6.8.12-1","6.8.12-1~bpo12+1","6.8.9-1","6.9.10-1","6.9.10-1~bpo12+1","6.9.11-1","6.9.12-1","6.9.2-1~exp1","6.9.7-1","6.9.7-1~bpo12+1","6.9.8-1","6.9.9-1","7.0-1~exp1","7.0.1-1~exp1","7.0.10-1","7.0.10-1~bpo13+1","7.0.12-1","7.0.12-2","7.0.12-2~bpo13+1","7.0.13-1","7.0.13-1~bpo13+1","7.0.14-1","7.0.3-1","7.0.4-1","7.0.4-1~bpo13+1","7.0.7-1","7.0.7-1~bpo13+1","7.0.9-1","7.0.9-1~bpo13+1","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