[Xen-devel] [PATCH 1/2] xl: fix adding configuration parameters over command line

[Andre Przywara <andre.przywara@xxxxxxx>]

Hi,

since we read the configuration text file as is from the disk, there is 
no trailing \0 at the end terminating the C string. Therefore we
must not use strcat to this buffer. Also we need to allocate
space for the trailing zero byte.
This is needed to make the command line appending actually work, 
otherwise I get a parser error due to memory trash.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12

commit 1b3e5056e47769b3a58f624ae933a227ab6b8b24
Author: Andre Przywara <andre.przywara@xxxxxxx>
Date:   Fri Sep 10 14:26:40 2010 +0200

    fix adding configuration parameters over command line
    
    Since we read the text file as is from the disk, there is no
    trailing \0 at the end terminating the C string. Therefore we
    must not use strcat to this buffer. Also we need to allocate
    space for the trailing zero byte.
    
    Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index e7b9d74..f40de2b 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1397,22 +1397,20 @@ static int create_domain(struct domain_create *dom_info)
                                        &config_data, &config_len);
         if (ret) { fprintf(stderr, "Failed to read config file: %s: %s\n",
                            config_file, strerror(errno)); return ERROR_FAIL; }
-        if (!restore_file && extra_config
-            && strlen(extra_config)) {
-            if (config_len > INT_MAX - (strlen(extra_config) + 2)) {
+        if (!restore_file && extra_config && strlen(extra_config)) {
+            if (config_len > INT_MAX - (strlen(extra_config) + 2 + 1)) {
                 fprintf(stderr, "Failed to attach extra configration\n");
                 return ERROR_FAIL;
             }
+            /* allocate space for the extra config plus two EOLs plus \0 */
             config_data = realloc(config_data, config_len
-                + strlen(extra_config) + 2);
+                + strlen(extra_config) + 2 + 1);
             if (!config_data) {
                 fprintf(stderr, "Failed to realloc config_data\n");
                 return ERROR_FAIL;
             }
-            strcat(config_data, "\n");
-            strcat(config_data, extra_config);
-            strcat(config_data, "\n");
-            config_len += (strlen(extra_config) + 2);
+            config_len += sprintf(config_data + config_len, "\n%s\n",
+                extra_config);
         }
     } else {
         if (!config_data) {

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