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From:   Muchun Song <songmuchun@bytedance.com>
To:     gregkh@linuxfoundation.org, rafael@kernel.org, david@redhat.com,
        cheloha@linux.vnet.ibm.com, mhocko@suse.com,
        akpm@linux-foundation.org, nathanl@linux.ibm.com
Cc:     linux-kernel@vger.kernel.org,
        Muchun Song <songmuchun@bytedance.com>, stable@vger.kernel.org
Subject: [PATCH] mm: memory_hotplug: fix memory error handling
Date:   Mon, 30 May 2022 13:33:26 +0800
Message-Id: <20220530053326.41682-1-songmuchun@bytedance.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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The device_unregister() is supposed to be used to unregister devices if
device_register() has succeed.  And device_unregister() will put device.
The caller should not do it again, otherwise, the first call of
put_device() will drop the last reference count, then the next call
of device_unregister() will UAF on device.

Fixes: 4fb6eabf1037 ("drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
---
 drivers/base/memory.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 7222ff9b5e05..084d67fd55cc 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -636,10 +636,9 @@ static int __add_memory_block(struct memory_block *memory)
 	}
 	ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
 			      GFP_KERNEL));
-	if (ret) {
-		put_device(&memory->dev);
+	if (ret)
 		device_unregister(&memory->dev);
-	}
+
 	return ret;
 }
 
-- 
2.11.0