linux-kernel - [PATCH] usb: gadget: Fix double free of device descriptor pointers

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Message-Id: <1618862240-5965-1-git-send-email-wcheng@codeaurora.org>
Date:   Mon, 19 Apr 2021 12:57:20 -0700
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     balbi@...nel.org, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        jackp@...eaurora.org, Hemant Kumar <hemantk@...eaurora.org>,
        Wesley Cheng <wcheng@...eaurora.org>
Subject: [PATCH] usb: gadget: Fix double free of device descriptor pointers

From: Hemant Kumar <hemantk@...eaurora.org>

Upon driver unbind usb_free_all_descriptors() function frees all
speed descriptor pointers without setting them to NULL. In case
gadget speed changes (i.e from super speed plus to super speed)
after driver unbind only upto super speed descriptor pointers get
populated. Super speed plus desc still holds the stale (already
freed) pointer. Fix this issue by setting all descriptor pointers
to NULL after freeing them in usb_free_all_descriptors().

Signed-off-by: Hemant Kumar <hemantk@...eaurora.org>
Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
---
 drivers/usb/gadget/config.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c
index 2d11535..8bb2577 100644
--- a/drivers/usb/gadget/config.c
+++ b/drivers/usb/gadget/config.c
@@ -194,9 +194,13 @@ EXPORT_SYMBOL_GPL(usb_assign_descriptors);
 void usb_free_all_descriptors(struct usb_function *f)
 {
 	usb_free_descriptors(f->fs_descriptors);
+	f->fs_descriptors = NULL;
 	usb_free_descriptors(f->hs_descriptors);
+	f->hs_descriptors = NULL;
 	usb_free_descriptors(f->ss_descriptors);
+	f->ss_descriptors = NULL;
 	usb_free_descriptors(f->ssp_descriptors);
+	f->ssp_descriptors = NULL;
 }
 EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
 
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