kernel/ums-realtek-driver-uses-stack-memory-for-DMA.patch
2011-08-16 10:32:18 -04:00

144 lines
4.7 KiB
Diff
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

From patchwork Tue Aug 2 05:04:11 2011
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: ums-realtek driver uses stack memory for DMA
Date: Tue, 02 Aug 2011 05:04:11 -0000
From: Adam Cozzette <acozzette@cs.hmc.edu>
X-Patchwork-Id: 1028062
Message-Id: <20110802050411.GC3857@[192.168.0.12]>
To: Josh Boyer <jwboyer@redhat.com>
Cc: edwin_rong <edwin_rong@realsil.com.cn>, wwang <wei_wang@realsil.com.cn>,
Greg Kroah-Hartman <gregkh@suse.de>, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
On Mon, Aug 01, 2011 at 05:09:06PM -0400, Josh Boyer wrote:
> Hello,
>
> We have a report that the ums-realtek driver is generating a backtrace
> due to using stack variables for DMA buffers. The backtrace is below
> and you can view the bug report here:
> https://bugzilla.redhat.com/show_bug.cgi?id=720054
>
> Looking through the code, it seems that every call to rts51x_read_mem,
> rts51x_write_mem, and rts51x_read_status passes a stack variable to
> rts51x_bulk_transport, which then calls usb_stor_bulk_transfer_buf with
> this and generates the backtrace. It is my understanding that the
> driver should be passing variables that are not on the stack and have
> been allocated with memory that will be suitable for the DMA api (e.g.
> kmalloc).
>
> Was this missed during the initial review and is anyone working on
> adapting the driver to be compliant?
Could you try out this patch if it looks ok to you? I have not tested it because
unfortunately I don't have the hardware. Right now it generates some compile
warnings like this one:
drivers/usb/storage/realtek_cr.c:419:40: warning: buf[0] may be used uninitialized in this function [-Wuninitialized]
It think they are harmless but I didn't see an obvious way to get rid of them,
so if you have any suggestions I would be glad to hear them.
This patch changed rts51x_read_mem, rts51x_write_mem, and rts51x_read_status to
allocate temporary buffers with kmalloc. This way stack addresses are not used
for DMA when these functions call rts51x_bulk_transport.
Signed-off-by: Adam Cozzette <acozzette@cs.hmc.edu>
---
realtek_cr.c | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c
index 34adc4b..232167a 100644
--- a/drivers/usb/storage/realtek_cr.c
+++ b/drivers/usb/storage/realtek_cr.c
@@ -320,6 +320,11 @@ static int rts51x_read_mem(struct us_data *us, u16 addr, u8 *data, u16 len)
{
int retval;
u8 cmnd[12] = { 0 };
+ u8 *buf;
+
+ buf = kmalloc(len, GFP_NOIO);
+ if (buf == NULL)
+ return USB_STOR_TRANSPORT_ERROR;
US_DEBUGP("%s, addr = 0x%x, len = %d\n", __func__, addr, len);
@@ -331,10 +336,14 @@ static int rts51x_read_mem(struct us_data *us, u16 addr, u8 *data, u16 len)
cmnd[5] = (u8) len;
retval = rts51x_bulk_transport(us, 0, cmnd, 12,
- data, len, DMA_FROM_DEVICE, NULL);
- if (retval != USB_STOR_TRANSPORT_GOOD)
+ buf, len, DMA_FROM_DEVICE, NULL);
+ if (retval != USB_STOR_TRANSPORT_GOOD) {
+ kfree(buf);
return -EIO;
+ }
+ memcpy(data, buf, len);
+ kfree(buf);
return 0;
}
@@ -342,6 +351,12 @@ static int rts51x_write_mem(struct us_data *us, u16 addr, u8 *data, u16 len)
{
int retval;
u8 cmnd[12] = { 0 };
+ u8 *buf;
+
+ buf = kmalloc(len, GFP_NOIO);
+ if (buf == NULL)
+ return USB_STOR_TRANSPORT_ERROR;
+ memcpy(buf, data, len);
US_DEBUGP("%s, addr = 0x%x, len = %d\n", __func__, addr, len);
@@ -353,7 +368,8 @@ static int rts51x_write_mem(struct us_data *us, u16 addr, u8 *data, u16 len)
cmnd[5] = (u8) len;
retval = rts51x_bulk_transport(us, 0, cmnd, 12,
- data, len, DMA_TO_DEVICE, NULL);
+ buf, len, DMA_TO_DEVICE, NULL);
+ kfree(buf);
if (retval != USB_STOR_TRANSPORT_GOOD)
return -EIO;
@@ -365,6 +381,11 @@ static int rts51x_read_status(struct us_data *us,
{
int retval;
u8 cmnd[12] = { 0 };
+ u8 *buf;
+
+ buf = kmalloc(len, GFP_NOIO);
+ if (buf == NULL)
+ return USB_STOR_TRANSPORT_ERROR;
US_DEBUGP("%s, lun = %d\n", __func__, lun);
@@ -372,10 +393,14 @@ static int rts51x_read_status(struct us_data *us,
cmnd[1] = 0x09;
retval = rts51x_bulk_transport(us, lun, cmnd, 12,
- status, len, DMA_FROM_DEVICE, actlen);
- if (retval != USB_STOR_TRANSPORT_GOOD)
+ buf, len, DMA_FROM_DEVICE, actlen);
+ if (retval != USB_STOR_TRANSPORT_GOOD) {
+ kfree(buf);
return -EIO;
+ }
+ memcpy(status, buf, len);
+ kfree(buf);
return 0;
}