linux-kernel - [PATCH] Staging:gasket:core: Fix a double free in gasket_enable

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Date:   Tue, 27 Apr 2021 07:11:29 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     rspringer@...gle.com, toddpoynor@...gle.com, benchan@...omium.org,
        rcy@...gle.com, gregkh@...uxfoundation.org
Cc:     linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] Staging:gasket:core: Fix a double free in gasket_enable_device

In gasket_enable_device, it calls gasket_interrupt_init().
Inside gasket_interrupt_init, interrupt_data is allocated via
kzalloc() and then is assigned to gasket_dev->interrupt_data.
If the later two kzalloc() failed, interrupt_data will be freed
and gasket_dev->interrupt_data will point to a freed memory.

After gasket_enable_device received the error, the freed
gasket_dev->interrupt_data is freed again in
gasket_interrupt_cleanup(gasket_dev).

My patch moves the "gasket_dev->interrupt_data = interrupt_data"
assignment behind the later kzalloc() all successd, to avoid
gasket_dev->interrupt_data pointing to a freed memory

Fixes: 80666096eb78f ("staging: gasket: core: remove static function forward declarations")
Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 drivers/staging/gasket/gasket_interrupt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/gasket/gasket_interrupt.c b/drivers/staging/gasket/gasket_interrupt.c
index 864342acfd86..d4993d7abb87 100644
--- a/drivers/staging/gasket/gasket_interrupt.c
+++ b/drivers/staging/gasket/gasket_interrupt.c
@@ -322,7 +322,6 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
 	interrupt_data = kzalloc(sizeof(*interrupt_data), GFP_KERNEL);
 	if (!interrupt_data)
 		return -ENOMEM;
-	gasket_dev->interrupt_data = interrupt_data;
 	interrupt_data->name = driver_desc->name;
 	interrupt_data->type = driver_desc->interrupt_type;
 	interrupt_data->pci_dev = gasket_dev->pci_dev;
@@ -349,6 +348,8 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
 		return -ENOMEM;
 	}
 
+	gasket_dev->interrupt_data = interrupt_data;
+
 	switch (interrupt_data->type) {
 	case PCI_MSIX:
 		ret = gasket_interrupt_msix_init(interrupt_data);
-- 
2.25.1