From 04eefabaae59ad624f0baf3b97a1d1d15cf2a23d Mon Sep 17 00:00:00 2001

From: David Gibson <david@gibson.dropbear.id.au>

Date: Mon, 10 Sep 2012 12:30:56 +1000

Subject: [PATCH] qemu-char: BUGFIX, don't call FD_ISSET with negative fd

tcp_chr_connect(), unlike for example udp_chr_update_read_handler() does

not check if the fd it is using is valid (>= 0) before passing it to

qemu_set_fd_handler2().  If using e.g. a TCP serial port, which is not

initially connected, this can result in -1 being passed to FD_ISSET, which

has undefined behaviour.  On x86 it seems to harmlessly return 0, but on

PowerPC, it causes a fortify buffer overflow error to be thrown.

This patch fixes this by putting an extra test in tcp_chr_connect(), and

also adds an assert qemu_set_fd_handler2() to catch other such errors on

all platforms, rather than just some.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

(cherry picked from commit bbdd2ad0814ea0911076419ea21b7957505cf1cc)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

---

 iohandler.c | 2 ++

 qemu-char.c | 6 ++++--

 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/iohandler.c b/iohandler.c

index dea4355..a2d871b 100644

--- a/iohandler.c

+++ b/iohandler.c

@@ -56,6 +56,8 @@ int qemu_set_fd_handler2(int fd,

 {

     IOHandlerRecord *ioh;

+    assert(fd >= 0);

+

     if (!fd_read && !fd_write) {

         QLIST_FOREACH(ioh, &io_handlers, next) {

             if (ioh->fd == fd) {

diff --git a/qemu-char.c b/qemu-char.c

index 10d1504..7f0f895 100644

--- a/qemu-char.c

+++ b/qemu-char.c

@@ -2329,8 +2329,10 @@ static void tcp_chr_connect(void *opaque)

     TCPCharDriver *s = chr->opaque;

     s->connected = 1;

-    qemu_set_fd_handler2(s->fd, tcp_chr_read_poll,

-                         tcp_chr_read, NULL, chr);

+    if (s->fd >= 0) {

+        qemu_set_fd_handler2(s->fd, tcp_chr_read_poll,

+                             tcp_chr_read, NULL, chr);

+    }

     qemu_chr_generic_open(chr);

 }

-- 

1.7.12.1