[Qemu-devel] [PATCH] qemu-char: Check for missing backend name

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

Check if the backend option is missing before searching the backend
table.  This fixes a NULL pointer dereference when QEMU is invoked with
the following invalid command-line:

  $ qemu -chardev id=foo,path=/tmp/socket

Previously QEMU would segfault, now it produces this error message:

  chardev: "foo" missing backend

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 qemu-char.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index edc9ad6..8a424d6 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2508,6 +2508,11 @@ CharDriverState *qemu_chr_open_opts(QemuOpts *opts,
         return NULL;
     }
 
+    if (qemu_opt_get(opts, "backend") == NULL) {
+        fprintf(stderr, "chardev: \"%s\" missing backend\n",
+                qemu_opts_id(opts));
+        return NULL;
+    }
     for (i = 0; i < ARRAY_SIZE(backend_table); i++) {
         if (strcmp(backend_table[i].name, qemu_opt_get(opts, "backend")) == 0)
             break;
-- 
1.7.2.3