linux-kernel - [PATCH] misc/libmasm/module: Fix two use after free in ibmasm_init

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Message-Id: <20210426170620.10546-1-lyl2019@mail.ustc.edu.cn>
Date:   Mon, 26 Apr 2021 10:06:20 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     arnd@...db.de, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] misc/libmasm/module: Fix two use after free in ibmasm_init_one

In ibmasm_init_one, it calls ibmasm_init_remote_input_dev().
Inside ibmasm_init_remote_input_dev, mouse_dev and keybd_dev are
allocated by input_allocate_device(), and assigned to
sp->remote.mouse_dev and sp->remote.keybd_dev respectively.

In the err_free_devices error branch of ibmasm_init_one,
mouse_dev and keybd_dev are freed by input_free_device(), and return
error. Then the execution runs into error_send_message error branch
of ibmasm_init_one, where ibmasm_free_remote_input_dev(sp) is called
to unregister the freed sp->remote.mouse_dev and sp->remote.keybd_dev.

My patch add a "error_init_remote" label to handle the error of
ibmasm_init_remote_input_dev(), to avoid the uaf bugs.

Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 drivers/misc/ibmasm/module.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/ibmasm/module.c b/drivers/misc/ibmasm/module.c
index 4edad6c445d3..dc8a06c06c63 100644
--- a/drivers/misc/ibmasm/module.c
+++ b/drivers/misc/ibmasm/module.c
@@ -111,7 +111,7 @@ static int ibmasm_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	result = ibmasm_init_remote_input_dev(sp);
 	if (result) {
 		dev_err(sp->dev, "Failed to initialize remote queue\n");
-		goto error_send_message;
+		goto error_init_remote;
 	}

 	result = ibmasm_send_driver_vpd(sp);
@@ -131,8 +131,9 @@ static int ibmasm_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	return 0;

 error_send_message:
-	disable_sp_interrupts(sp->base_address);
 	ibmasm_free_remote_input_dev(sp);
+error_init_remote:
+	disable_sp_interrupts(sp->base_address);
 	free_irq(sp->irq, (void *)sp);
 error_request_irq:
 	iounmap(sp->base_address);
-- 
2.25.1