diff options
| author | Zhang Cen <rollkingzzc@gmail.com> | 2026-05-24 19:12:48 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:32:22 -0700 |
| commit | bbd5e0bb48084a399ffd184f937124c0cb96c130 (patch) | |
| tree | e8250ed1f97b6f683eb144f0b490da4126275593 /fs | |
| parent | 5eb0bda367c2dbc8c9de9539c3c63015e1d1315e (diff) | |
| download | linux-next-history-bbd5e0bb48084a399ffd184f937124c0cb96c130.tar.gz | |
ocfs2: reject oversized group bitmap descriptors
ocfs2_validate_gd_parent() only bounds bg_bits against the parent
allocator's chain geometry. A malicious descriptor can still claim a
bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in
the group descriptor block, so later bitmap scans and bit updates can run
past bg_bitmap.
Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent
allocator type and reject descriptors whose bg_size or bg_bits exceed that
capacity. Keep the existing chain geometry check so both the on-disk
bitmap layout and the allocator metadata must agree before the descriptor
is used.
Validation reproduced this kernel report:
KASAN use-after-free in _find_next_bit+0x7f/0xc0
Read of size 8
Call trace:
dump_stack_lvl+0x66/0xa0 (?:?)
print_report+0xd0/0x630 (?:?)
_find_next_bit+0x7f/0xc0 (?:?)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x188/0x2f0 (?:?)
kasan_report+0xe4/0x120 (?:?)
ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)
ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)
ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)
ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)
ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)
get_page_from_freelist+0x70e/0x2370 (?:?)
lock_release+0xc6/0x290 (?:?)
do_raw_spin_unlock+0x9a/0x100 (?:?)
kasan_unpoison+0x27/0x60 (?:?)
__bfs+0x147/0x240 (?:?)
get_page_from_freelist+0x83d/0x2370 (?:?)
ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)
sched_domains_numa_masks_clear+0x70/0xd0 (?:?)
check_irq_usage+0xe8/0xb70 (?:?)
__ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)
check_path+0x24/0x50 (?:?)
rcu_is_watching+0x20/0x50 (?:?)
check_prev_add+0xfd/0xd00 (?:?)
ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)
__folio_batch_add_and_move+0x1f5/0x3d0 (?:?)
ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)
filemap_add_folio+0x105/0x1f0 (?:?)
ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)
ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)
down_write+0xf5/0x180 (?:?)
ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)
__mark_inode_dirty+0x758/0x9a0 (?:?)
inode_to_bdi+0x41/0x90 (?:?)
balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)
generic_perform_write+0x252/0x440 (?:?)
mnt_put_write_access_file+0x16/0x70 (?:?)
file_update_time_flags+0xe4/0x200 (?:?)
ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)
lock_acquire+0x184/0x2f0 (?:?)
ksys_write+0xd2/0x170 (?:?)
apparmor_file_permission+0xf5/0x310 (?:?)
read_zero+0x8d/0x140 (?:?)
lock_is_held_type+0x8f/0x100 (?:?)
Link: https://lore.kernel.org/20260524111248.1429884-1-rollkingzzc@gmail.com
Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Zhang Cen <rollkingzzc@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ocfs2/suballoc.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index d284e0e372525..a4a2b87a45fe3 100644 --- a/fs/ocfs2/suballoc.c +++ b/fs/ocfs2/suballoc.c @@ -231,8 +231,16 @@ static int ocfs2_validate_gd_parent(struct super_block *sb, int resize) { unsigned int max_bits; + unsigned int max_bitmap_bits; + unsigned int max_bitmap_size; + int suballocator; struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data; + suballocator = le64_to_cpu(di->i_blkno) != OCFS2_SB(sb)->bitmap_blkno; + max_bitmap_size = ocfs2_group_bitmap_size(sb, suballocator, + OCFS2_SB(sb)->s_feature_incompat); + max_bitmap_bits = max_bitmap_size * 8; + if (di->i_blkno != gd->bg_parent_dinode) { do_error("Group descriptor #%llu has bad parent pointer (%llu, expected %llu)\n", (unsigned long long)bh->b_blocknr, @@ -240,6 +248,20 @@ static int ocfs2_validate_gd_parent(struct super_block *sb, (unsigned long long)le64_to_cpu(di->i_blkno)); } + if (le16_to_cpu(gd->bg_size) > max_bitmap_size) { + do_error("Group descriptor #%llu has bitmap size %u but physical max of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(gd->bg_size), + max_bitmap_size); + } + + if (le16_to_cpu(gd->bg_bits) > max_bitmap_bits) { + do_error("Group descriptor #%llu has bit count %u but physical max of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(gd->bg_bits), + max_bitmap_bits); + } + max_bits = le16_to_cpu(di->id2.i_chain.cl_cpg) * le16_to_cpu(di->id2.i_chain.cl_bpc); if (le16_to_cpu(gd->bg_bits) > max_bits) { do_error("Group descriptor #%llu has bit count of %u\n", |