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List:       linux-stable-commits
Subject:    patch fix-zero-length-socket-write-semantics.patch queued to -stable tree
From:       <gregkh () suse ! de>
Date:       2007-10-10 20:07:33
Message-ID: 20071010200742.D28A21454471 () imap ! suse ! de
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This is a note to let you know that we have just queued up the patch titled

     Subject: Fix zero length socket write() semantics.

to the 2.6.22-stable tree.  Its filename is

     fix-zero-length-socket-write-semantics.patch

A git repo of this tree can be found at 
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


From stable-bounces@linux.kernel.org Wed Oct 10 03:21:47 2007
From: David S. Miller <davem@sunset.davemloft.net>
Date: Wed, 10 Oct 2007 03:21:37 -0700 (PDT)
Subject: Fix zero length socket write() semantics.
To: stable@kernel.org
Cc: bunk@kernel.org
Message-ID: <20071010.032137.91314889.davem@davemloft.net>

From: David S. Miller <davem@sunset.davemloft.net>

changeset e79ad711a0108475c1b3a03815527e7237020b08 from mainline.

This fixes kernel bugzilla #5731

It should generate an empty packet for datagram protocols when the
socket is connected, for one.

The check is doubly-wrong because all that a write() can be is a
sendmsg() call with a NULL msg_control and a single entry iovec.  No
special semantics should be assigned to it, therefore the zero length
check should be removed entirely.

This matches the behavior of BSD and several other systems.

Alan Cox notes that SuSv3 says the behavior of a zero length write on
non-files is "unspecified", but that's kind of useless since BSD has
defined this behavior for a quarter century and BSD is essentially
what application folks code to.

Based upon a patch from Stephen Hemminger.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

--- a/net/socket.c
+++ b/net/socket.c
@@ -777,9 +777,6 @@ static ssize_t sock_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	if (pos != 0)
 		return -ESPIPE;
 
-	if (iocb->ki_left == 0)	/* Match SYS5 behaviour */
-		return 0;
-
 	x = alloc_sock_iocb(iocb, &siocb);
 	if (!x)
 		return -ENOMEM;
-- 
1.5.3.2

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Patches currently in stable-queue which might be from davem@sunset.davemloft.net are

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