linux-kernel - [PATCH 3/3] fs/btrfs: avoid null pointer dereference if reloc control has not been initialized

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Message-Id: <1609080931-4048864-1-git-send-email-bodefang@126.com>
Date:   Sun, 27 Dec 2020 22:55:31 +0800
From:   Defang Bo <bodefang@....com>
To:     clm@...com, josef@...icpanda.com, dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Defang Bo <bodefang@....com>
Subject: [PATCH 3/3] fs/btrfs: avoid null pointer dereference if reloc control has not been initialized

Similar to commmit<389305b2>, it turns out that fs_info::reloc_ctl can be NULL ,
so there should be a check for rc to prevent null pointer dereference.

Signed-off-by: Defang Bo <bodefang@....com>
---
 fs/btrfs/relocation.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 3602806..ca03571 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -626,6 +626,9 @@ static int __must_check __add_reloc_root(struct btrfs_root *root)
 	struct mapping_node *node;
 	struct reloc_control *rc = fs_info->reloc_ctl;
 
+	if (!rc)
+		return 0;
+
 	node = kmalloc(sizeof(*node), GFP_NOFS);
 	if (!node)
 		return -ENOMEM;
@@ -703,6 +706,9 @@ static int __update_reloc_root(struct btrfs_root *root)
 	struct rb_node *rb_node;
 	struct mapping_node *node = NULL;
 	struct reloc_control *rc = fs_info->reloc_ctl;
+
+	if (!rc)
+		return 0;
 
 	spin_lock(&rc->reloc_root_tree.lock);
 	rb_node = rb_simple_search(&rc->reloc_root_tree.rb_root,
-- 
2.7.4