[PATCH] libxl: don't segfault when creating domain with invalid pvusb device

[Juergen Gross <jgross@suse.com>]

Creating a domain with an invalid controller specification for a pvusb
device will currently segfault.

Avoid this by bailing out early in case of a mandatory xenstore path
not existing.

Signed-of-by: Juergen Gross <jgross@suse.com>
---
This patch is a backport candidate for 4.8
---
 tools/libxl/libxl_usb.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl_usb.c b/tools/libxl/libxl_usb.c
index ea7a2ab..b235507 100644
--- a/tools/libxl/libxl_usb.c
+++ b/tools/libxl/libxl_usb.c
@@ -651,12 +651,13 @@ int libxl_device_usbctrl_getinfo(libxl_ctx *ctx, uint32_t domid,
 
     usbctrlinfo->devid = usbctrl->devid;
 
-#define READ_SUBPATH(path, subpath) ({                                  \
-        rc = libxl__xs_read_checked(gc, XBT_NULL,                       \
-                                    GCSPRINTF("%s/" subpath, path),     \
-                                    &tmp);                              \
-        if (rc) goto out;                                               \
-        (char *)tmp;                                                    \
+#define READ_SUBPATH(path, subpath) ({                                      \
+        tmp = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/" subpath, path)); \
+        if (!tmp) {                                                         \
+            rc = ERROR_FAIL;                                                \
+            goto out;                                                       \
+        }                                                                   \
+        (char *)tmp;                                                        \
     })
 
 #define READ_SUBPATH_INT(path, subpath) ({                              \
-- 
2.10.2


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel