linux-kernel - [PATCH 4.4 20/24] USB: core: Change %pK for _

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Date:   Tue,  1 Dec 2020 09:53:26 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Vamsi Krishna Samavedam <vskrishn@...eaurora.org>,
        Alan Stern <stern@...land.harvard.edu>
Subject: [PATCH 4.4 20/24] USB: core: Change %pK for __user pointers to %px

From: Alan Stern <stern@...land.harvard.edu>

commit f3bc432aa8a7a2bfe9ebb432502be5c5d979d7fe upstream.

Commit 2f964780c03b ("USB: core: replace %p with %pK") used the %pK
format specifier for a bunch of __user pointers.  But as the 'K' in
the specifier indicates, it is meant for kernel pointers.  The reason
for the %pK specifier is to avoid leaks of kernel addresses, but when
the pointer is to an address in userspace the security implications
are minimal.  In particular, no kernel information is leaked.

This patch changes the __user %pK specifiers (used in a bunch of
debugging output lines) to %px, which will always print the actual
address with no mangling.  (Notably, there is no printk format
specifier particularly intended for __user pointers.)

Fixes: 2f964780c03b ("USB: core: replace %p with %pK")
CC: Vamsi Krishna Samavedam <vskrishn@...eaurora.org>
CC: <stable@...r.kernel.org>
Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Link: https://lore.kernel.org/r/20201119170228.GB576844@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/core/devio.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -369,11 +369,11 @@ static void snoop_urb(struct usb_device

 	if (userurb) {		/* Async */
 		if (when == SUBMIT)
-			dev_info(&udev->dev, "userurb %pK, ep%d %s-%s, "
+			dev_info(&udev->dev, "userurb %px, ep%d %s-%s, "
 					"length %u\n",
 					userurb, ep, t, d, length);
 		else
-			dev_info(&udev->dev, "userurb %pK, ep%d %s-%s, "
+			dev_info(&udev->dev, "userurb %px, ep%d %s-%s, "
 					"actual_length %u status %d\n",
 					userurb, ep, t, d, length,
 					timeout_or_status);