Syzbot test for v2 for fs: ocfs2: fix kernel BUG in ocfs2_find_victim_chain

[Prithvi Tambewagh <activprithvi@gmail.com>]

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 939f15e640f193616691d3bcde0089760e75b0d3

Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
---
 fs/ocfs2/suballoc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 6ac4dcd54588..f4e4ef08e0f9 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1992,6 +1992,13 @@ static int ocfs2_claim_suballoc_bits(struct ocfs2_alloc_context *ac,
 	}
 
 	cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
+	if (!le16_to_cpu(cl->cl_next_free_rec) ||
+		le16_to_cpu(cl->cl_next_free_rec) > le16_to_cpu(cl->cl_count)) {
+		status = ocfs2_error(ac->ac_inode->i_sb,
+				     "Chain allocator dinode %llu has 0 chains\n",
+				     (unsigned long long)le64_to_cpu(fe->i_blkno));
+		goto bail;
+	}
 
 	victim = ocfs2_find_victim_chain(cl);
 	ac->ac_chain = victim;

base-commit: 939f15e640f193616691d3bcde0089760e75b0d3
-- 
2.34.1