From: Chunfeng Yun <chunfeng.yun@mediatek.com>
Date: Thu, 28 Apr 2016 03:42:20 +0000 (+0800)
Subject: usb: core: buffer: avoid NULL pointer dereferrence
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=f5e6253fe6de35fc2fa059974dbd9d61f32e4cd0;p=deliverable%2Flinux.git

usb: core: buffer: avoid NULL pointer dereferrence

NULL pointer dereferrence will happen when class driver
wants to allocate zero length buffer and pool_max[0]
can't be used, so simply returns NULL in the case.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
index 2741566ee4f2..98e39f91723a 100644
--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -122,6 +122,9 @@ void *hcd_buffer_alloc(
 	struct usb_hcd		*hcd = bus_to_hcd(bus);
 	int			i;
 
+	if (size == 0)
+		return NULL;
+
 	/* some USB hosts just use PIO */
 	if (!IS_ENABLED(CONFIG_HAS_DMA) ||
 	    (!bus->controller->dma_mask &&