USB: gadget: zero allocate endpoint 0 buffers

stable inclusion
from stable-v5.10.85
commit e4de8ca013f06ad4a0bf40420a291c23990e4131
bugzilla: 186032 https://gitee.com/openeuler/kernel/issues/I4QVI4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e4de8ca013f06ad4a0bf40420a291c23990e4131

--------------------------------

commit 86ebbc11 upstream.

Under some conditions, USB gadget devices can show allocated buffer
contents to a host.  Fix this up by zero-allocating them so that any
extra data will all just be zeros.
Reported-by: NSzymon Heidrich <szymon.heidrich@gmail.com>
Tested-by: NSzymon Heidrich <szymon.heidrich@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/usb/gadget/legacy/dbgp.c

@@ -137,7 +137,7 @@ static int dbgp_enable_ep_req(struct usb_ep *ep)
 		goto fail_1;
 	}
 
-	req->buf = kmalloc(DBGP_REQ_LEN, GFP_KERNEL);
+	req->buf = kzalloc(DBGP_REQ_LEN, GFP_KERNEL);
 	if (!req->buf) {
 		err = -ENOMEM;
 		stp = 2;