On Tue, Nov 08, 2016 at 11:43:09AM +0100, Richard Weinberger wrote:
> Don't pass a size larger than iov_len to kernel_sendmsg().
> Otherwise it will cause a NULL pointer deref when kernel_sendmsg()
> returns with rv < size.
>
> Although the issue exists since day 0, only on non-ancient kernels
> that contain change 57be5bdad759 ("ip: convert tcp_sendmsg() to iov_iter
> primitives") it seems to trigger [0][1][2][3][4].
The real fix here is to convert it to the right primitive, e.g. take
Al's patch from here:
https://git.kernel.org/cgit/linux/kernel/git/viro/vfs.git/commit/?h=work.sendmsg&id=7a4992299554a9e1ed3c4540bcfa9e40aa9a6376
