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Subject[PATCH] ums_realtek: do not use stack memory for DMA
This patch changes 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(-)

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;
}

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