[Qemu-devel] [RESEND PATCH] monitor: properly handle illegal fd/vhostfd from command line

[Jason Wang <jasowang@redhat.com>]

When hanlding fd/vhostfd form command line through net_handle_fd_param(),
we need to check mon and return value of strtol() other than we could
get segmentation fault or invalid fd when user type an illegal fd/vhostfd.

This patch is based on the suggestions from
Luiz Capitulino <lcapitulino@redhat.com>.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 net.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/net.c b/net.c
index ed74c7f..ab9c3bb 100644
--- a/net.c
+++ b/net.c
@@ -774,8 +774,8 @@ int qemu_find_nic_model(NICInfo *nd, const char * const *models,
 
 int net_handle_fd_param(Monitor *mon, const char *param)
 {
-    if (!qemu_isdigit(param[0])) {
-        int fd;
+    int fd;
+    if (!qemu_isdigit(param[0]) && mon) {
 
         fd = monitor_get_fd(mon, param);
         if (fd == -1) {
@@ -785,7 +785,13 @@ int net_handle_fd_param(Monitor *mon, const char *param)
 
         return fd;
     } else {
-        return strtol(param, NULL, 0);
+        char *endptr = NULL;
+
+        fd = strtol(param, &endptr, 10);
+        if (*endptr || (fd == 0 && param == endptr)) {
+            return -1;
+        }
+        return fd;
     }
 }