[PATCH]libxc: fix a Segmentation fault

[PATCH]libxc: fix a Segmentation fault

[Yang Hongyang]

# xl list
xc: error: Could not obtain handle on privileged command interface (2 = No such file or directory): Internal error
Segmentation fault

This is because xc free the logger which xl created.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com> 

diff -r b622e411eef8 tools/libxc/xc_private.c
--- a/tools/libxc/xc_private.c	Thu Jun 24 21:56:03 2010 +0100
+++ b/tools/libxc/xc_private.c	Mon Jun 28 22:48:07 2010 +0800
@@ -19,6 +19,7 @@
                                 xentoollog_logger *dombuild_logger,
                                 unsigned open_flags) {
     xc_interface xch_buf, *xch = &xch_buf;
+    int init_handler = 0;
 
     xch->fd = -1;
     xch->dombuild_logger_file = 0;
@@ -33,6 +34,7 @@
             xtl_createlogger_stdiostream(stderr, XTL_PROGRESS, 0);
         if (!xch->error_handler)
             goto err;
+        init_handler =1;
     }
 
     xch = malloc(sizeof(*xch));
@@ -52,7 +54,7 @@
     return xch;
 
  err:
-    if (xch) xtl_logger_destroy(xch->error_handler);
+    if (xch && init_handler) xtl_logger_destroy(xch->error_handler);
     if (xch != &xch_buf) free(xch);
     return 0;
 }

-- 
Regards
Yang Hongyang

Re: [PATCH]libxc: fix a Segmentation fault

[Ian Jackson]

Yang Hongyang writes ("[Xen-devel] [PATCH]libxc: fix a Segmentation fault"):
> # xl list
> xc: error: Could not obtain handle on privileged command interface (2 = No such file or directory): Internal error
> Segmentation fault
> 
> This is because xc free the logger which xl created.

Well spotted.  You're right about the cause, but your fix is not
correct.  The correct fix is that xc_interface_open's error path
should free error_handler_tofree rather than error_handler.  So there
is no need to add another variable.  I will apply that fix.

Thanks,
Ian.

Re: [PATCH]libxc: fix a Segmentation fault

[Yang Hongyang]

On 06/28/2010 11:54 PM, Ian Jackson wrote:
> Yang Hongyang writes ("[Xen-devel] [PATCH]libxc: fix a Segmentation fault"):
>> # xl list
>> xc: error: Could not obtain handle on privileged command interface (2 = No such file or directory): Internal error
>> Segmentation fault
>>
>> This is because xc free the logger which xl created.
> 
> Well spotted.  You're right about the cause, but your fix is not
> correct.  The correct fix is that xc_interface_open's error path
> should free error_handler_tofree rather than error_handler.  So there
> is no need to add another variable.  I will apply that fix.
> 

OK,Thanks Ian.

> Thanks,
> Ian.
> 
> 


-- 
Regards
Yang Hongyang