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From 5813402bce6119ed5241d72e6000584a12a490ea Mon Sep 17 00:00:00 2001
From: Eric Blake <>
Date: Mon, 10 Jul 2017 16:28:19 +0200
Subject: [PATCH 4/4] qemu-nbd: Ignore SIGPIPE

RH-Author: Eric Blake <>
Message-id: <>
Patchwork-id: 75717
O-Subject: [RHEV-7.4.z qemu-kvm-rhev PATCH] qemu-nbd: Ignore SIGPIPE
Bugzilla: 1469463
RH-Acked-by: John Snow <>
RH-Acked-by: Stefan Hajnoczi <>
RH-Acked-by: Miroslav Rezanina <>

From: Max Reitz <>

qemu proper has done so for 13 years
(8a7ddc38a60648257dc0645ab4a05b33d6040063), qemu-img and qemu-io have
done so for four years (526eda14a68d5b3596be715505289b541288ef2a).
Ignoring this signal is especially important in qemu-nbd because
otherwise a client can easily take down the qemu-nbd server by dropping
the connection when the server wants to send something, for example:

$ qemu-nbd -x foo -f raw -t null-co:// &
[1] 12726
$ qemu-io -c quit nbd://localhost/bar
can't open device nbd://localhost/bar: No export with name 'bar' available
[1]  + 12726 broken pipe  qemu-nbd -x foo -f raw -t null-co://

In this case, the client sends an NBD_OPT_ABORT and closes the
connection (because it is not required to wait for a reply), but the
server replies with an NBD_REP_ACK (because it is required to reply).

Signed-off-by: Max Reitz <>
Message-Id: <>
Signed-off-by: Paolo Bonzini <>
(cherry picked from commit 041e32b8d9d076980b4e35317c0339e57ab888f1)
Fixes CVE-2017-10664
Signed-off-by: Eric Blake <>

Signed-off-by: Miroslav Rezanina <>
 qemu-nbd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 483dd77..5deb37e 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -581,6 +581,10 @@ int main(int argc, char **argv)
     sa_sigterm.sa_handler = termsig_handler;
     sigaction(SIGTERM, &sa_sigterm, NULL);
+    signal(SIGPIPE, SIG_IGN);