Hello,
I've found an integer overflow vulnerability in the cpia2 driver's
mmap implementation , allowing an attacker to map area outside of the
frame's buffer, giving him a primitive that possibly can be used to
privilege escalations. The security list confirmed the bug and asked
me to suggest a patch, and send it to you. I'm attaching the patch
file here.
If you would like to get the exploit code , or the explanations I sent
to the security list , please let me know.
I look forward to receiving your updates.
Best regards,
Omer Shalev.
diff --git a/drivers/media/usb/cpia2/cpia2_core.c b/drivers/media/usb/cpia2/cpia2_core.c
index 20c50c2d042e..97e610eb3895 100644
--- a/drivers/media/usb/cpia2/cpia2_core.c
+++ b/drivers/media/usb/cpia2/cpia2_core.c
@@ -2390,8 +2390,8 @@ int cpia2_remap_buffer(struct camera_data *cam, struct vm_area_struct *vma)
{
const char *adr = (const char *)vma->vm_start;
unsigned long size = vma->vm_end-vma->vm_start;
- unsigned long start_offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long start = (unsigned long) adr;
+ unsigned long start_offset;
unsigned long page, pos;
DBG("mmap offset:%ld size:%ld\n", start_offset, size);
@@ -2399,9 +2399,14 @@ int cpia2_remap_buffer(struct camera_data *cam, struct vm_area_struct *vma)
if (!video_is_registered(&cam->vdev))
return -ENODEV;
+ if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
+ return -EINVAL;
+
+ start_offset = vma->vm_pgoff << PAGE_SHIFT;
+
if (size > cam->frame_size*cam->num_frames ||
(start_offset % cam->frame_size) != 0 ||
- (start_offset+size > cam->frame_size*cam->num_frames))
+ (start_offset > cam->frame_size*cam->num_frames -size))
return -EINVAL;
pos = ((unsigned long) (cam->frame_buffer)) + start_offset;
