* [PATCH v3] libxl: don't segfault when creating domain with invalid pvusb device
@ 2017-02-08 13:34 Juergen Gross
2017-02-08 14:35 ` Ian Jackson
0 siblings, 1 reply; 3+ messages in thread
From: Juergen Gross @ 2017-02-08 13:34 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, wei.liu2, ian.jackson
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
V2: introduce libxl__xs_read_mandatory() as suggested by Ian Jackson
V3: adjust comment as requested 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 5f46578..a093bc6 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -738,6 +738,13 @@ int libxl__xs_mknod(libxl__gc *gc, xs_transaction_t t,
/* 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
*/
int libxl__xs_read_checked(libxl__gc *gc, xs_transaction_t t,
diff --git a/tools/libxl/libxl_usb.c b/tools/libxl/libxl_usb.c
index ea7a2ab..d8948d5 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 a50805f..c4a18df 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)
{
--
2.10.2
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] libxl: don't segfault when creating domain with invalid pvusb device
2017-02-08 13:34 [PATCH v3] libxl: don't segfault when creating domain with invalid pvusb device Juergen Gross
@ 2017-02-08 14:35 ` Ian Jackson
2017-02-08 15:40 ` Wei Liu
0 siblings, 1 reply; 3+ messages in thread
From: Ian Jackson @ 2017-02-08 14:35 UTC (permalink / raw)
To: Juergen Gross; +Cc: xen-devel, wei.liu2
Juergen Gross writes ("[PATCH v3] 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.
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Good choice of function name, thanks.
Ian.
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] libxl: don't segfault when creating domain with invalid pvusb device
2017-02-08 14:35 ` Ian Jackson
@ 2017-02-08 15:40 ` Wei Liu
0 siblings, 0 replies; 3+ messages in thread
From: Wei Liu @ 2017-02-08 15:40 UTC (permalink / raw)
To: Ian Jackson; +Cc: Juergen Gross, xen-devel, wei.liu2
On Wed, Feb 08, 2017 at 02:35:53PM +0000, Ian Jackson wrote:
> Juergen Gross writes ("[PATCH v3] 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.
>
> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Applied.
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2017-02-08 13:34 [PATCH v3] libxl: don't segfault when creating domain with invalid pvusb device Juergen Gross
2017-02-08 14:35 ` Ian Jackson
2017-02-08 15:40 ` Wei Liu
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