qemu-char: avoid segfault if user lacks of permisson of a given logfile

Function qemu_chr_alloc returns NULL if it failed to open logfile by any reason,
says no write permission. For backends tty, stdio and msmouse, They need to
check this return value to avoid segfault in this case.

Signed-off-by: Lin Ma <lma@suse.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Message-Id: <20160914062250.22226-1-lma@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 71200fb9664c2967a1cdd22b68b0da3a8b2b3eb7)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/backends/msmouse.c b/backends/msmouse.c
index aeb905562d2fb4ce311789c122831637a16c4cf6..aceb6dc475748efa026c536e49125aaea231e43b 100644 (file)
--- a/backends/msmouse.c
+++ b/backends/msmouse.c
@@ -159,6 +159,9 @@ static CharDriverState *qemu_chr_open_msmouse(const char *id,
     CharDriverState *chr;
 
     chr = qemu_chr_alloc(common, errp);
+    if (!chr) {
+        return NULL;
+    }
     chr->chr_write = msmouse_chr_write;
     chr->chr_close = msmouse_chr_close;
     chr->chr_accept_input = msmouse_chr_accept_input;

diff --git a/qemu-char.c b/qemu-char.c
index 5f82ebb774c00e5b909f7b92ef47981f9ed24ecb..fdb23f52896643595ab7f3a33f2926e5744e53bc 100644 (file)
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -1223,6 +1223,9 @@ static CharDriverState *qemu_chr_open_stdio(const char *id,
     sigaction(SIGCONT, &act, NULL);
 
     chr = qemu_chr_open_fd(0, 1, common, errp);
+    if (!chr) {
+        return NULL;
+    }
     chr->chr_close = qemu_chr_close_stdio;
     chr->chr_set_echo = qemu_chr_set_echo_stdio;
     if (opts->has_signal) {
@@ -1679,6 +1682,9 @@ static CharDriverState *qemu_chr_open_tty_fd(int fd,
 
     tty_serial_init(fd, 115200, 'N', 8, 1);
     chr = qemu_chr_open_fd(fd, fd, backend, errp);
+    if (!chr) {
+        return NULL;
+    }
     chr->chr_ioctl = tty_serial_ioctl;
     chr->chr_close = qemu_chr_close_tty;
     return chr;