[PATCH 1/2] ocfs2: validate orphan slot during inode read

[ZhengYuan Huang <gality369@gmail.com>]

[BUG]
A corrupted dinode with OCFS2_ORPHANED_FL can carry an
i_orphaned_slot outside the mounted filesystem slot range.
ocfs2_wipe_inode() uses it to index osb_orphan_wipes before looking
up the orphan directory, causing an out-of-bounds memory access.

BUG: KASAN: slab-use-after-free in ocfs2_get_system_file_inode+0x780/0x820 fs/ocfs2/sysfile.c:102
Read of size 8 at addr ffff88800b767c00 by task kworker/u8:3/85
Call Trace:
 ...
 ocfs2_get_system_file_inode+0x780/0x820 fs/ocfs2/sysfile.c:102
 ocfs2_wipe_inode+0x292/0xf70 fs/ocfs2/inode.c:840
 ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
 ocfs2_evict_inode+0x6c9/0x1170 fs/ocfs2/inode.c:1295
 evict+0x38e/0x8f0 fs/inode.c:810
 iput_final fs/inode.c:1914 [inline]
 iput fs/inode.c:1966 [inline]
 iput+0x55b/0x8b0 fs/inode.c:1926
 ocfs2_recover_orphans+0x610/0xe40 fs/ocfs2/journal.c:2374
 ocfs2_complete_recovery+0x5af/0xd00 fs/ocfs2/journal.c:1373
 ...

[CAUSE]
ocfs2_validate_inode_block() validates i_suballoc_slot but leaves
the active ordinary orphan slot unchecked. Downstream consumers
assume that the value is smaller than osb->max_slots.

[FIX]
Reject an active i_orphaned_slot outside the slot range during
dinode validation, before the inode reaches orphan wipe processing.

Fixes: b4df6ed8db0c ("[PATCH] ocfs2: fix orphan recovery deadlock")
Signed-off-by: ZhengYuan Huang <gality369@gmail.com>
---
 fs/ocfs2/inode.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 41db7dd39ed9..358ab3535366 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1528,6 +1528,14 @@ int ocfs2_validate_inode_block(struct super_block *sb,
 		goto bail;
 	}
 
+	if ((le32_to_cpu(di->i_flags) & OCFS2_ORPHANED_FL) &&
+	    le16_to_cpu(di->i_orphaned_slot) >= OCFS2_SB(sb)->max_slots) {
+		rc = ocfs2_error(sb, "Invalid dinode %llu: orphaned slot %u\n",
+				 (unsigned long long)bh->b_blocknr,
+				 le16_to_cpu(di->i_orphaned_slot));
+		goto bail;
+	}
+
 	/*
 	 * Reject dinodes whose i_mode does not name one of the seven
 	 * canonical POSIX file types.  ocfs2_populate_inode() copies
-- 
2.43.0