linux-kernel - [PATCH -next 2/3] ubifs: fix double return leb in ubifs_garbage

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Date:   Mon, 15 Nov 2021 09:31:43 +0800
From:   Baokun Li <libaokun1@...wei.com>
To:     <richard@....at>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <libaokun1@...wei.com>, <yukuai3@...wei.com>,
        Hulk Robot <hulkci@...wei.com>
Subject: [PATCH -next 2/3] ubifs: fix double return leb in ubifs_garbage_collect

If ubifs_garbage_collect_leb() returns -EAGAIN and enters the "out"
branch, ubifs_return_leb will execute twice on the same lnum. This
can cause data loss in concurrency situations.

Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 fs/ubifs/gc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index 05e1eeae8457..1f74a127fe3a 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -758,6 +758,8 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
 				err = ubifs_return_leb(c, lp.lnum);
 				if (err)
 					ret = err;
+				/*  Maybe double return LEB if goto out */
+				lp.lnum = -1;
 				break;
 			}
 			goto out;
-- 
2.31.1