[PATCH 2/4] zr364xx: enforce minimum size when reading header

[Alyssa Milburn]

This code copies actual_length-128 bytes from the header, which will
underflow if the received buffer is too small.

Signed-off-by: Alyssa Milburn <amilb...@zall.org>
---
 drivers/media/usb/zr364xx/zr364xx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/media/usb/zr364xx/zr364xx.c 
b/drivers/media/usb/zr364xx/zr364xx.c
index f2d6fc03dda0..efdcd5bd6a4c 100644
--- a/drivers/media/usb/zr364xx/zr364xx.c
+++ b/drivers/media/usb/zr364xx/zr364xx.c
@@ -600,6 +600,14 @@ static int zr364xx_read_video_callback(struct 
zr364xx_camera *cam,
        ptr = pdest = frm->lpvbits;
 
        if (frm->ulState == ZR364XX_READ_IDLE) {
+               if (purb->actual_length < 128) {
+                       /* header incomplete */
+                       dev_info(&cam->udev->dev,
+                                "%s: buffer (%d bytes) too small to hold jpeg 
header. Discarding.\n",
+                                __func__, purb->actual_length);
+                       return -EINVAL;
+               }
+
                frm->ulState = ZR364XX_READ_FRAME;
                frm->cur_size = 0;
 
-- 
2.11.0