CVE-2026-63796

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ocfs2: reject oversized group bitmap descriptors<br /> <br /> ocfs2_validate_gd_parent() only bounds bg_bits against the parent<br /> allocator&amp;#39;s chain geometry. A malicious descriptor can still claim a<br /> bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in<br /> the group descriptor block, so later bitmap scans and bit updates can run<br /> past bg_bitmap.<br /> <br /> Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent<br /> allocator type and reject descriptors whose bg_size or bg_bits exceed that<br /> capacity. Keep the existing chain geometry check so both the on-disk<br /> bitmap layout and the allocator metadata must agree before the descriptor<br /> is used.<br /> <br /> Validation reproduced this kernel report:<br /> KASAN use-after-free in _find_next_bit+0x7f/0xc0<br /> Read of size 8<br /> Call trace:<br /> dump_stack_lvl+0x66/0xa0 (?:?)<br /> print_report+0xd0/0x630 (?:?)<br /> _find_next_bit+0x7f/0xc0 (?:?)<br /> srso_alias_return_thunk+0x5/0xfbef5 (?:?)<br /> __virt_addr_valid+0x188/0x2f0 (?:?)<br /> kasan_report+0xe4/0x120 (?:?)<br /> ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)<br /> ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)<br /> ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)<br /> ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)<br /> ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)<br /> get_page_from_freelist+0x70e/0x2370 (?:?)<br /> lock_release+0xc6/0x290 (?:?)<br /> do_raw_spin_unlock+0x9a/0x100 (?:?)<br /> kasan_unpoison+0x27/0x60 (?:?)<br /> __bfs+0x147/0x240 (?:?)<br /> get_page_from_freelist+0x83d/0x2370 (?:?)<br /> ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)<br /> sched_domains_numa_masks_clear+0x70/0xd0 (?:?)<br /> check_irq_usage+0xe8/0xb70 (?:?)<br /> __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)<br /> check_path+0x24/0x50 (?:?)<br /> rcu_is_watching+0x20/0x50 (?:?)<br /> check_prev_add+0xfd/0xd00 (?:?)<br /> ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)<br /> __folio_batch_add_and_move+0x1f5/0x3d0 (?:?)<br /> ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)<br /> filemap_add_folio+0x105/0x1f0 (?:?)<br /> ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)<br /> ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)<br /> down_write+0xf5/0x180 (?:?)<br /> ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)<br /> __mark_inode_dirty+0x758/0x9a0 (?:?)<br /> inode_to_bdi+0x41/0x90 (?:?)<br /> balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)<br /> generic_perform_write+0x252/0x440 (?:?)<br /> mnt_put_write_access_file+0x16/0x70 (?:?)<br /> file_update_time_flags+0xe4/0x200 (?:?)<br /> ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)<br /> lock_acquire+0x184/0x2f0 (?:?)<br /> ksys_write+0xd2/0x170 (?:?)<br /> apparmor_file_permission+0xf5/0x310 (?:?)<br /> read_zero+0x8d/0x140 (?:?)<br /> lock_is_held_type+0x8f/0x100 (?:?)