patch "usb: core: safely deal with the dynamic quirk lists" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    usb: core: safely deal with the dynamic quirk lists

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 16c4cb19fa85c648a803752eb63cac0ef69231c2 Mon Sep 17 00:00:00 2001
From: Harry Pan <harry.pan@intel.com>
Date: Fri, 14 Sep 2018 16:58:16 +0800
Subject: usb: core: safely deal with the dynamic quirk lists

Applying dynamic usbcore quirks in early booting when the slab is
not yet ready would cause kernel panic of null pointer dereference
because the quirk_count has been counted as 1 while the quirk_list
was failed to allocate.

i.e.,
[    1.044970] BUG: unable to handle kernel NULL pointer dereference at           (null)
[    1.044995] IP: [<ffffffffb0953ec7>] usb_detect_quirks+0x88/0xd1
[    1.045016] PGD 0
[    1.045026] Oops: 0000 [#1] PREEMPT SMP
[    1.046986] gsmi: Log Shutdown Reason 0x03
[    1.046995] Modules linked in:
[    1.047008] CPU: 0 PID: 81 Comm: kworker/0:3 Not tainted 4.4.154 #28
[    1.047016] Hardware name: Google Coral/Coral, BIOS Google_Coral.10068.27.0 12/04/2017
[    1.047028] Workqueue: usb_hub_wq hub_event
[    1.047037] task: ffff88017a321c80 task.stack: ffff88017a384000
[    1.047044] RIP: 0010:[<ffffffffb0953ec7>]  [<ffffffffb0953ec7>] usb_detect_quirks+0x88/0xd1

To tackle this odd, let's balance the quirk_count to 0 when the kcalloc
call fails, and defer the quirk setting into a lower level callback
which ensures that the kernel memory management has been initialized.

Fixes: 027bd6cafd9a ("usb: core: Add "quirks" parameter for usbcore")
Signed-off-by: Harry Pan <harry.pan@intel.com>
Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/core/quirks.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index e77dfe5ed5ec..178d6c6063c0 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -58,6 +58,7 @@ static int quirks_param_set(const char *val, const struct kernel_param *kp)
 	quirk_list = kcalloc(quirk_count, sizeof(struct quirk_entry),
 			     GFP_KERNEL);
 	if (!quirk_list) {
+		quirk_count = 0;
 		mutex_unlock(&quirk_mutex);
 		return -ENOMEM;
 	}
@@ -154,7 +155,7 @@ static struct kparam_string quirks_param_string = {
 	.string = quirks_param,
 };
 
-module_param_cb(quirks, &quirks_param_ops, &quirks_param_string, 0644);
+device_param_cb(quirks, &quirks_param_ops, &quirks_param_string, 0644);
 MODULE_PARM_DESC(quirks, "Add/modify USB quirks by specifying quirks=vendorID:productID:quirks");
 
 /* Lists of quirky USB devices, split in device quirks and interface quirks.
-- 
2.19.0