From 58b4db0832de1ee355a342feea7e1545219bef12 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 8 Feb 2017 14:34:08 +0100 Subject: [PATCH] libxl: don't segfault when creating domain with invalid pvusb device 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 Acked-by: Ian Jackson Acked-by: Wei Liu --- tools/libxl/libxl_internal.h | 7 +++++++ tools/libxl/libxl_usb.c | 6 +++--- tools/libxl/libxl_xshelp.c | 12 ++++++++++++ 3 files changed, 22 insertions(+), 3 deletions(-) diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index 5f46578b9b..a093bc62ee 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -736,6 +736,13 @@ int libxl__xs_mknod(libxl__gc *gc, xs_transaction_t t, const char *path, struct xs_permissions *perms, unsigned int num_perms); +/* On success, *result_out came from the gc. + * On error, *result_out is undefined. + * ENOENT is regarded as error. + */ +int libxl__xs_read_mandatory(libxl__gc *gc, xs_transaction_t t, + const char *path, const char **result_out); + /* On success, *result_out came from the gc. * On error, *result_out is undefined. * ENOENT counts as success but sets *result_out=0 diff --git a/tools/libxl/libxl_usb.c b/tools/libxl/libxl_usb.c index ea7a2abed4..d8948d5212 100644 --- a/tools/libxl/libxl_usb.c +++ b/tools/libxl/libxl_usb.c @@ -652,9 +652,9 @@ 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); \ + rc = libxl__xs_read_mandatory(gc, XBT_NULL, \ + GCSPRINTF("%s/" subpath, path), \ + &tmp); \ if (rc) goto out; \ (char *)tmp; \ }) diff --git a/tools/libxl/libxl_xshelp.c b/tools/libxl/libxl_xshelp.c index a50805fcec..c4a18df353 100644 --- a/tools/libxl/libxl_xshelp.c +++ b/tools/libxl/libxl_xshelp.c @@ -193,6 +193,18 @@ char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid) return s; } +int libxl__xs_read_mandatory(libxl__gc *gc, xs_transaction_t t, + const char *path, const char **result_out) +{ + char *result = libxl__xs_read(gc, t, path); + if (!result) { + LOGE(ERROR, "xenstore read failed: `%s'", path); + return ERROR_FAIL; + } + *result_out = result; + return 0; +} + int libxl__xs_read_checked(libxl__gc *gc, xs_transaction_t t, const char *path, const char **result_out) { -- 2.30.2