Re: [PATCH RFC net v3 7/7] net/iucv: return EOF to a reader parked when the peer closes

[sashiko-bot@kernel.org]

> From: Bryam Vargas <hexlabsecurity@proton.me>
> 
> A recvmsg() that starts after the peer closed returns 0. One that was
> already waiting returns -ENOTCONN: its wait ends on sk_state and does
> not ask whether anything is left to read. In a z/VM guest over
> HiperSockets that was every parked reader, 13627 of 13627 on net-next
> [1]. poll() does not report EPOLLRDHUP for the close either.
> 
> Return EOF from the wait too when the socket is IUCV_DISCONN with
> nothing left to read. As for a call that starts afterwards, it does not
> matter how the socket got there: the peer's FIN, a severed z/VM path, a
> transmit error, a window update that could not be sent or the device
> going down. EOF does not say that all the peer sent was read: a severed
> z/VM path drops the messages not yet received, for either call. Set
> RCV_SHUTDOWN where the HiperSockets FIN is applied, as TCP does: poll()
> then reports EPOLLRDHUP and EPOLLRDNORM for the close, and EPOLLHUP if
> the socket had shut down its own sending. The other ways still report
> none of the three.
> 
> Fixes: 561e036006dc ("[AF_IUCV]: Implementation of a skb backlog queue")
> Fixes: 3881ac441f64 ("af_iucv: add HiperSockets transport")
> Reported-by: Hidayath Khan <hidayath@linux.ibm.com>
> Closes: https://lore.kernel.org/netdev/82691101-92d7-4838-b16e-2e41a83f65d0@linux.ibm.com/
> Link: https://lore.kernel.org/netdev/51a4a40a-f34b-4d41-b049-69aa53f4dcf5@linux.ibm.com/ [1]
> Cc: stable@vger.kernel.org # 6.18.x
> Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>

Sashiko has reviewed this patch and found no issues.

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