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Subject[PATCH v3] usbnet/cdc_ncm: Don't use stack variables for DMA
From 1717b6b8b1de95ed4ca53b74d2ccb563fae9b898 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Tue, 2 Aug 2011 08:09:56 -0400
Subject: [PATCH] usbnet/cdc_ncm: Don't use stack variables for DMA buffers

The cdc_ncm driver still has a few places where stack variables are passed
to the cdc_ncm_do_request function. This triggers a stack trace in
lib/dma-debug.c if the CONFIG_DEBUG_DMA_API option is set.

Adjust these calls to pass parameters that have been allocated with kzalloc.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---

v3: Fix checkpatch errors
v2: Fix leak in error path

drivers/net/usb/cdc_ncm.c | 54 +++++++++++++++++++++++++++++++++++----------
1 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index fd622a6..bbcb133 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -260,23 +260,39 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)
req.wIndex = cpu_to_le16(iface_no);

if (flags & USB_CDC_NCM_NCAP_NTB_INPUT_SIZE) {
- struct usb_cdc_ncm_ndp_input_size ndp_in_sz;
+ struct usb_cdc_ncm_ndp_input_size *ndp_in_sz;
+
+ ndp_in_sz = kzalloc(sizeof(*ndp_in_sz), GFP_KERNEL);
+ if (!ndp_in_sz) {
+ err = -ENOMEM;
+ goto size_err;
+ }

req.wLength = 8;
- ndp_in_sz.dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);
- ndp_in_sz.wNtbInMaxDatagrams =
+ ndp_in_sz->dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);
+ ndp_in_sz->wNtbInMaxDatagrams =
cpu_to_le16(CDC_NCM_DPT_DATAGRAMS_MAX);
- ndp_in_sz.wReserved = 0;
- err = cdc_ncm_do_request(ctx, &req, &ndp_in_sz, 0, NULL,
+ ndp_in_sz->wReserved = 0;
+ err = cdc_ncm_do_request(ctx, &req, ndp_in_sz, 0, NULL,
1000);
+ kfree(ndp_in_sz);
} else {
- __le32 dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);
+ __le32 *dwNtbInMaxSize;
+ dwNtbInMaxSize = kzalloc(sizeof(*dwNtbInMaxSize),
+ GFP_KERNEL);
+ if (!dwNtbInMaxSize) {
+ err = -ENOMEM;
+ goto size_err;
+ }
+ *dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);

req.wLength = 4;
- err = cdc_ncm_do_request(ctx, &req, &dwNtbInMaxSize, 0,
+ err = cdc_ncm_do_request(ctx, &req, dwNtbInMaxSize, 0,
NULL, 1000);
+ kfree(dwNtbInMaxSize);
}

+size_err:
if (err)
pr_debug("Setting NTB Input Size failed\n");
}
@@ -362,9 +378,16 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)

/* set Max Datagram Size (MTU) */
if (flags & USB_CDC_NCM_NCAP_MAX_DATAGRAM_SIZE) {
- __le16 max_datagram_size;
+ __le16 *max_datagram_size;
u16 eth_max_sz = le16_to_cpu(ctx->ether_desc->wMaxSegmentSize);

+ max_datagram_size = kzalloc(sizeof(*max_datagram_size),
+ GFP_KERNEL);
+ if (!max_datagram_size) {
+ err = -ENOMEM;
+ goto max_dgram_err;
+ }
+
req.bmRequestType = USB_TYPE_CLASS | USB_DIR_IN |
USB_RECIP_INTERFACE;
req.bNotificationType = USB_CDC_GET_MAX_DATAGRAM_SIZE;
@@ -372,13 +395,17 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)
req.wIndex = cpu_to_le16(iface_no);
req.wLength = cpu_to_le16(2);

- err = cdc_ncm_do_request(ctx, &req, &max_datagram_size, 0, NULL,
+ err = cdc_ncm_do_request(ctx, &req, max_datagram_size, 0, NULL,
1000);
+
if (err) {
pr_debug("GET_MAX_DATAGRAM_SIZE failed, use size=%u\n",
CDC_NCM_MIN_DATAGRAM_SIZE);
+ kfree(max_datagram_size);
} else {
- ctx->max_datagram_size = le16_to_cpu(max_datagram_size);
+ ctx->max_datagram_size =
+ le16_to_cpu(*max_datagram_size);
+
/* Check Eth descriptor value */
if (eth_max_sz < CDC_NCM_MAX_DATAGRAM_SIZE) {
if (ctx->max_datagram_size > eth_max_sz)
@@ -401,10 +428,13 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)
req.wValue = 0;
req.wIndex = cpu_to_le16(iface_no);
req.wLength = 2;
- max_datagram_size = cpu_to_le16(ctx->max_datagram_size);
+ *max_datagram_size =
+ cpu_to_le16(ctx->max_datagram_size);

- err = cdc_ncm_do_request(ctx, &req, &max_datagram_size,
+ err = cdc_ncm_do_request(ctx, &req, max_datagram_size,
0, NULL, 1000);
+ kfree(max_datagram_size);
+max_dgram_err:
if (err)
pr_debug("SET_MAX_DATAGRAM_SIZE failed\n");
}
--
1.7.6


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