usb: core: safely deal with the dynamic quirk lists

Harry Pan · gregkh · commit 16c4cb19fa85 · 2018-09-20T13:20:24.000+02:00
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 torvalds#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: 027bd6c ("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>
diff --git 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.
