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>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c
index 34adc4b42ceb7b564277e96e89b0869bc5563550..232167ad47811c3c4ac5f1f0ad4feead43275dd6 100644 (file)
--- 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;
 }