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If anyone has any objections, please let me know. ------------------ From: Joseph Qi [ Upstream commit 25bf9e549360b656a6763232e0e9e58a00c3aff7 ] Patch series "ocfs2: validate suballoc slot and bit of metadata blocks", v3. The ocfs2 metadata validators trust the on-disk suballoc slot and bit without checking them against the slot range of the mounted filesystem and the capacity of the block group bitmap. A corrupted image can carry OCFS2_INVALID_SLOT or another out-of-range slot, or a suballoc bit beyond the bitmap, and once the corresponding inode, extent block, xattr block, dir index root or refcount block gets freed, the bad value goes straight into ocfs2_get_system_file_inode() or _ocfs2_free_suballoc_bits() and hits a BUG_ON() or runs off the end of local_system_inodes[]. This series rejects such values at read time, in the existing validators, so corrupted objects fail with -EROFS (and a read-only remount) instead of crashing: patch 1 restricts OCFS2_INVALID_SLOT dinodes to system inodes, completing fe7a283b3916 ("ocfs2: add suballoc slot check in ocfs2_validate_inode_block()"), and turns the "system file state is ambiguous" BUG_ON() in ocfs2_read_locked_inode() into an ocfs2_error(); patch 2 rejects oversized dinode suballoc bits; patch 3 validates the suballoc slot and bit of xattr and dir index blocks; patch 4 validates the suballoc slot and bit of extent and refcount blocks. The checks only enforce what the kernel and mkfs.ocfs2 already write: a valid slot from meta_ac->ac_alloc_slot and a bit within the block group bitmap, with system inodes carrying OCFS2_INVALID_SLOT plus OCFS2_SYSTEM_FL and extent blocks using slot 0. Nothing changes for healthy filesystems. Each new check was exercised under QEMU by corrupting the field in question with an out-of-range value; with the series applied the access fails with -EROFS and the filesystem remounts read-only instead of hitting the BUG_ON(). This patch (of 4): ocfs2_validate_inode_block() currently permits i_suballoc_slot to be OCFS2_INVALID_SLOT for any dinode. Only system inodes created by mkfs.ocfs2 are allocated from the global allocator and thus legitimately carry this value; regular inodes are always allocated from a per-slot suballocator and hence must have a valid slot. If a corrupted regular inode with OCFS2_INVALID_SLOT is accepted, ocfs2_remove_inode() will pass the slot to ocfs2_get_system_file_inode() and get_local_system_inode() will hit BUG_ON(slot == OCFS2_INVALID_SLOT) when the inode is deleted. This can be triggered by an unprivileged user unlinking such a corrupted file. Reject OCFS2_INVALID_SLOT for non-system dinodes during validation, while still accepting it for system inodes. Note that a crafted dinode carrying OCFS2_SYSTEM_FL passes the check above, yet a plain lookup of it still used to BUG() in ocfs2_read_locked_inode() ("system file state is ambiguous"). Since i_flags comes from disk, handle that mismatch with ocfs2_error() instead of BUG_ON() as well. Link: https://lore.kernel.org/20260901125221.1634686-1-joseph.qi@linux.alibaba.com Link: https://lore.kernel.org/20260901125221.1634686-2-joseph.qi@linux.alibaba.com Fixes: fe7a283b3916 ("ocfs2: add suballoc slot check in ocfs2_validate_inode_block()") Signed-off-by: Joseph Qi Signed-off-by: Andrew Morton Cc: Changwei Ge Cc: Heming Zhao Cc: Joel Becker Cc: Jun Piao Cc: Junxiao Bi Cc: Mark Fasheh Cc: Signed-off-by: Sasha Levin --- fs/ocfs2/inode.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c index 835c00b90b7c8..c1ac673ca456d 100644 --- a/fs/ocfs2/inode.c +++ b/fs/ocfs2/inode.c @@ -637,14 +637,18 @@ static int ocfs2_read_locked_inode(struct inode *inode, fe = (struct ocfs2_dinode *) bh->b_data; /* - * This is a code bug. Right now the caller needs to - * understand whether it is asking for a system file inode or - * not so the proper lock names can be built. + * The caller must know whether it is asking for a system file inode + * or not so the proper lock names can be built. Since i_flags comes + * from disk, a mismatch is filesystem corruption instead of a code + * bug, so handle it with ocfs2_error() rather than BUG_ON(). */ - mlog_bug_on_msg(!!(fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL)) != - !!(args->fi_flags & OCFS2_FI_FLAG_SYSFILE), - "Inode %llu: system file state is ambiguous\n", - (unsigned long long)args->fi_blkno); + if (!!(fe->i_flags & cpu_to_le32(OCFS2_SYSTEM_FL)) != + !!(args->fi_flags & OCFS2_FI_FLAG_SYSFILE)) { + status = ocfs2_error(osb->sb, + "Inode %llu: system file state is ambiguous\n", + (unsigned long long)args->fi_blkno); + goto bail; + } if (S_ISCHR(le16_to_cpu(fe->i_mode)) || S_ISBLK(le16_to_cpu(fe->i_mode))) @@ -1530,8 +1534,23 @@ int ocfs2_validate_inode_block(struct super_block *sb, goto bail; } - if (le16_to_cpu(di->i_suballoc_slot) != (u16)OCFS2_INVALID_SLOT && - (u32)le16_to_cpu(di->i_suballoc_slot) > OCFS2_SB(sb)->max_slots - 1) { + /* + * Only system inodes created by mkfs.ocfs2 are allocated from the + * global allocator and thus legitimately carry OCFS2_INVALID_SLOT. + * Regular inodes are always allocated from a per-slot suballocator. + * If a regular inode with OCFS2_INVALID_SLOT was accepted here, + * deleting it would pass the slot to get_local_system_inode() via + * ocfs2_remove_inode() and trigger BUG_ON(slot == OCFS2_INVALID_SLOT). + */ + if (le16_to_cpu(di->i_suballoc_slot) == (u16)OCFS2_INVALID_SLOT) { + if (!(le32_to_cpu(di->i_flags) & OCFS2_SYSTEM_FL)) { + rc = ocfs2_error(sb, + "Invalid dinode %llu: suballoc slot %u for non-system inode\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(di->i_suballoc_slot)); + goto bail; + } + } else if ((u32)le16_to_cpu(di->i_suballoc_slot) > OCFS2_SB(sb)->max_slots - 1) { rc = ocfs2_error(sb, "Invalid dinode %llu: suballoc slot %u\n", (unsigned long long)bh->b_blocknr, le16_to_cpu(di->i_suballoc_slot)); -- 2.53.0