[Drbd-dev] [PATCH] drbd: Fix kernel_sendmsg() usage

Christoph Hellwig hch at infradead.org
Tue Nov 8 16:49:24 CET 2016

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:


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