netdev - [PATCH AUTOSEL 4.4 23/30] mwl8k: Fix use-after-free in mwl8k_fw_state

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Date:   Mon,  8 Nov 2021 20:09:11 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zheyu Ma <zheyuma97@...il.com>, Kalle Valo <kvalo@...eaurora.org>,
        Sasha Levin <sashal@...nel.org>, davem@...emloft.net,
        kuba@...nel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 23/30] mwl8k: Fix use-after-free in mwl8k_fw_state_machine()

From: Zheyu Ma <zheyuma97@...il.com>

[ Upstream commit 257051a235c17e33782b6e24a4b17f2d7915aaec ]

When the driver fails to request the firmware, it calls its error
handler. In the error handler, the driver detaches device from driver
first before releasing the firmware, which can cause a use-after-free bug.

Fix this by releasing firmware first.

The following log reveals it:

[    9.007301 ] BUG: KASAN: use-after-free in mwl8k_fw_state_machine+0x320/0xba0
[    9.010143 ] Workqueue: events request_firmware_work_func
[    9.010830 ] Call Trace:
[    9.010830 ]  dump_stack_lvl+0xa8/0xd1
[    9.010830 ]  print_address_description+0x87/0x3b0
[    9.010830 ]  kasan_report+0x172/0x1c0
[    9.010830 ]  ? mutex_unlock+0xd/0x10
[    9.010830 ]  ? mwl8k_fw_state_machine+0x320/0xba0
[    9.010830 ]  ? mwl8k_fw_state_machine+0x320/0xba0
[    9.010830 ]  __asan_report_load8_noabort+0x14/0x20
[    9.010830 ]  mwl8k_fw_state_machine+0x320/0xba0
[    9.010830 ]  ? mwl8k_load_firmware+0x5f0/0x5f0
[    9.010830 ]  request_firmware_work_func+0x172/0x250
[    9.010830 ]  ? read_lock_is_recursive+0x20/0x20
[    9.010830 ]  ? process_one_work+0x7a1/0x1100
[    9.010830 ]  ? request_firmware_nowait+0x460/0x460
[    9.010830 ]  ? __this_cpu_preempt_check+0x13/0x20
[    9.010830 ]  process_one_work+0x9bb/0x1100

Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
Link: https://lore.kernel.org/r/1634356979-6211-1-git-send-email-zheyuma97@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/mwl8k.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mwl8k.c b/drivers/net/wireless/mwl8k.c
index d448480b84063..073968eccbc2b 100644
--- a/drivers/net/wireless/mwl8k.c
+++ b/drivers/net/wireless/mwl8k.c
@@ -5783,8 +5783,8 @@ static void mwl8k_fw_state_machine(const struct firmware *fw, void *context)
 fail:
 	priv->fw_state = FW_STATE_ERROR;
 	complete(&priv->firmware_loading_complete);
-	device_release_driver(&priv->pdev->dev);
 	mwl8k_release_firmware(priv);
+	device_release_driver(&priv->pdev->dev);
 }
 
 #define MAX_RESTART_ATTEMPTS 1
-- 
2.33.0