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SubjectRe: 2.2.x BUG & PATCH: recvmsg() does not check msg_controllen correctly
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"David S. Miller" <davem@redhat.com> writes:

> The real bug is in the setting of MSG_TRUNC (which is the only side
> effect of your change). So the better fix is:
>
> --- net/core/scm.c.~1~ Tue Jun 15 09:19:30 1999
> +++ net/core/scm.c Fri Nov 3 14:18:06 2000
> @@ -251,7 +251,7 @@
> msg->msg_controllen -= cmlen;
> }
> }
> - if (i < fdnum)
> + if (i < fdnum || (fdnum && fdmax <= 0))
> msg->msg_flags |= MSG_CTRUNC;
>
> /*

Mmmh, no, if fdmax <= 0 (which happens when msg_controllen <
sizeof(struct cmsghdr)), then alls fds are passed, eventually
clobbering past ((char*)(msg_control)+m_controllen).

Run the little test case if you're not convinced...
I stand by my patch :-)

Phil.
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