Thread (32 messages) 32 messages, 11 authors, 2020-08-14

Re: [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak in rds_notify_queue_get()

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2020-07-31 05:33:38
Also in: linux-rdma, lkml, netdev

On Fri, Jul 31, 2020 at 07:33:06AM +0200, Greg Kroah-Hartman wrote:
On Fri, Jul 31, 2020 at 07:53:01AM +0300, Leon Romanovsky wrote:
quoted
On Thu, Jul 30, 2020 at 03:20:26PM -0400, Peilin Ye wrote:
quoted
rds_notify_queue_get() is potentially copying uninitialized kernel stack
memory to userspace since the compiler may leave a 4-byte hole at the end
of `cmsg`.

In 2016 we tried to fix this issue by doing `= { 0 };` on `cmsg`, which
unfortunately does not always initialize that 4-byte hole. Fix it by using
memset() instead.
Of course, this is the difference between "{ 0 }" and "{}" initializations.
Really?  Neither will handle structures with holes in it, try it and
see.
And if true, where in the C spec does it say that?

thanks,

greg k-h
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