From 7c1abe66f86c2e6af14908152c938a9ecec689d4 Mon Sep 17 00:00:00 2001 From: Joseph Qi Date: Tue, 1 Sep 2026 20:52:21 +0800 Subject: [PATCH] ocfs2: validate suballoc slot and bit of extent and refcount blocks ocfs2_validate_extent_block() and ocfs2_validate_refcount_block() do not validate h_suballoc_slot, h_suballoc_bit, rf_suballoc_slot and rf_suballoc_bit at all. Since extent blocks and refcount blocks are allocated from a per-slot suballocator at runtime, their suballoc slots must be within range and their suballoc bits must fit in a block group bitmap. Otherwise a corrupted image can carry an out-of-range slot. When the extent block is freed, ocfs2_cache_extent_block_free() caches it and ocfs2_free_cached_blocks() later passes the unvalidated slot to ocfs2_get_system_file_inode(); when the refcount block is freed, ocfs2_remove_refcount_extent() passes it via ocfs2_cache_block_dealloc(). get_local_system_inode() will then either hit BUG_ON(slot == OCFS2_INVALID_SLOT) or compute an out-of-bounds index into the local_system_inodes array. Similarly an oversized suballoc bit will error out the filesystem in _ocfs2_free_suballoc_bits(). Furthermore group descriptor validation only guarantees bg_bits within the physical bitmap size, so a corrupted image can still carry a suballoc bit beyond bg_bits, which would let ocfs2_block_group_clear_bits() clear bits beyond bg_bitmap. Convert the remaining BUG_ON against group->bg_bits in _ocfs2_free_suballoc_bits() to ocfs2_error() as well. Reject out-of-range suballoc slots and oversized suballoc bits during validation. Link: https://lore.kernel.org/20260901125221.1634686-5-joseph.qi@linux.alibaba.com Signed-off-by: Joseph Qi Signed-off-by: Andrew Morton Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao --- fs/ocfs2/alloc.c | 27 +++++++++++++++++++++++++++ fs/ocfs2/refcounttree.c | 27 +++++++++++++++++++++++++++ fs/ocfs2/suballoc.c | 15 ++++++++++++++- 3 files changed, 68 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c index be09e766ac1f..2fdc5403b10b 100644 --- a/fs/ocfs2/alloc.c +++ b/fs/ocfs2/alloc.c @@ -925,6 +925,33 @@ static int ocfs2_validate_extent_block(struct super_block *sb, goto bail; } + /* + * Extent blocks are allocated from a per-slot suballocator, so the + * slot must be in range. Otherwise freeing the block passes it to + * get_local_system_inode(), which hits BUG_ON() for + * OCFS2_INVALID_SLOT or computes an out-of-bounds index otherwise. + */ + if ((u32)le16_to_cpu(eb->h_suballoc_slot) >= OCFS2_SB(sb)->max_slots) { + rc = ocfs2_error(sb, + "Extent block #%llu has an invalid h_suballoc_slot of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(eb->h_suballoc_slot)); + goto bail; + } + + /* + * Similarly the suballoc bit must fit in a block group bitmap. + * Otherwise freeing the block will pass the oversized bit to + * _ocfs2_free_suballoc_bits() and trigger ocfs2_error() there. + */ + if (le16_to_cpu(eb->h_suballoc_bit) >= ocfs2_suballoc_bits_per_block(sb)) { + rc = ocfs2_error(sb, + "Extent block #%llu has an invalid h_suballoc_bit of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(eb->h_suballoc_bit)); + goto bail; + } + if (le16_to_cpu(eb->h_list.l_count) != ocfs2_extent_recs_per_eb(sb)) { rc = ocfs2_error(sb, "Extent block #%llu has invalid l_count %u (expected %u)\n", diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index d9f22b4a2654..3e9cccf06e48 100644 --- a/fs/ocfs2/refcounttree.c +++ b/fs/ocfs2/refcounttree.c @@ -117,6 +117,33 @@ static int ocfs2_validate_refcount_block(struct super_block *sb, goto out; } + /* + * Refcount blocks are allocated from a per-slot suballocator, so the + * slot must be in range. Otherwise freeing the block passes it to + * get_local_system_inode(), which hits BUG_ON() for + * OCFS2_INVALID_SLOT or computes an out-of-bounds index otherwise. + */ + if ((u32)le16_to_cpu(rb->rf_suballoc_slot) >= OCFS2_SB(sb)->max_slots) { + rc = ocfs2_error(sb, + "Refcount block #%llu has an invalid rf_suballoc_slot of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(rb->rf_suballoc_slot)); + goto out; + } + + /* + * Similarly the suballoc bit must fit in a block group bitmap. + * Otherwise freeing the block will pass the oversized bit to + * _ocfs2_free_suballoc_bits() and trigger ocfs2_error() there. + */ + if (le16_to_cpu(rb->rf_suballoc_bit) >= ocfs2_suballoc_bits_per_block(sb)) { + rc = ocfs2_error(sb, + "Refcount block #%llu has an invalid rf_suballoc_bit of %u\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(rb->rf_suballoc_bit)); + goto out; + } + /* * rf_records (rl_count/rl_used/rl_recs[]) is only meaningful when * this block is not an interior tree block (OCFS2_REFCOUNT_TREE_FL); diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index ce22d0c3d287..624152e4f7fe 100644 --- a/fs/ocfs2/suballoc.c +++ b/fs/ocfs2/suballoc.c @@ -3070,7 +3070,20 @@ static int _ocfs2_free_suballoc_bits(handle_t *handle, } group = (struct ocfs2_group_desc *) group_bh->b_data; - BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits)); + /* + * Group descriptor validation only guarantees bg_bits within the + * physical bitmap size, so double check the freeing range here. + * Otherwise ocfs2_block_group_clear_bits() would clear bits beyond + * bg_bitmap. + */ + if ((count + start_bit) > le16_to_cpu(group->bg_bits)) { + status = ocfs2_error(alloc_inode->i_sb, + "Group descriptor #%llu has %u bits, cannot free bits %u+%u\n", + (unsigned long long)le64_to_cpu(group->bg_blkno), + le16_to_cpu(group->bg_bits), + count, start_bit); + goto bail; + } if (ocfs2_is_cluster_bitmap(alloc_inode)) old_bg_contig_free_bits = group->bg_contig_free_bits;