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usb: core: safely deal with the dynamic quirk lists
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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: 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>
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Harry Pan authored and gregkh committed Sep 20, 2018
1 parent 5c54fca commit 16c4cb1
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion drivers/usb/core/quirks.c
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down Expand Up @@ -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.
Expand Down

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