On Sat, Dec 15, 2012 at 08:12:37PM +0000, Al Viro wrote: > Walking rbtree while it's modified is a Bad Idea(tm); besides, > the result of find_vma() can be freed just as it's getting returned > to caller. Fortunately, it's easy to fix - just take ->mmap_sem a bit > earlier (and don't bother with find_vma() at all if virtp >= PAGE_OFFSET - > in that case we don't even look at its result). While we are at it, what prevents VIDIOC_PREPARE_BUF calling v4l_prepare_buf() -> (e.g) vb2_ioctl_prepare_buf() -> vb2_prepare_buf() -> __buf_prepare() -> __qbuf_userptr() -> vb2_vmalloc_get_userptr() -> find_vma(), AFAICS without having taken ->mmap_sem anywhere in process? The code flow is bloody convoluted and depends on a bunch of things done by initialization, so I certainly might've missed something... -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
