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libxc: fix a Segmentation fault

PATCH In review Yang Hongyang 2 participants 3 messages Jun 28, 2010 – Jun 29, 2010

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Yang Hongyang

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#0 lore raw

PATCH 1/1 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.

Signed-off-by Yang Hongyang <[email protected]>
tools/libxc/xc_private.c +3 -1
diff -r b622e411eef8 tools/libxc/xc_private.c
@@ -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;
 }
Signature · 2 lines
Regards
Yang Hongyang
#1 lore raw

Yang Hongyang writes ("[Xen-devel] [PATCH]libxc: fix a Segmentation fault"):

Quoted 5 lines
# 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.

author
#2 lore raw
Quoted 5 lines · Ian Jackson

Yang Hongyang writes ("[Xen-devel] [PATCH]libxc: fix a Segmentation fault"):

Quoted 4 lines
# xl list
xc: error: Could not obtain handle on privileged command interface (2 = No such file or directory): Internal error
Segmentation fault
Quoted 7 lines
Quoted 1 line

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.

Quoted 4 lines

Thanks,
Ian.

Signature · 2 lines
Regards
Yang Hongyang