From: Florian Forster <octo@collectd.org>
Date: Mon, 5 Sep 2016 08:35:22 +0000 (+0200)
Subject: hugepages plugin: Don't use pathconf(_PC_NAME_MAX).
X-Git-Tag: collectd-5.7.0~93
X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=56a368209ea679eaa6790de419b68573505afb74;p=collectd.git

hugepages plugin: Don't use pathconf(_PC_NAME_MAX).

Since we allocate the buffer on the stack, this doesn't make sense:
Best case, the returned value is the same as the PATH_MAX define. Worst
case, the returned value is larger and we create a stack overflow.
---

diff --git a/src/hugepages.c b/src/hugepages.c
index 8573fc34..8e8391f4 100644
--- a/src/hugepages.c
+++ b/src/hugepages.c
@@ -160,7 +160,6 @@ static int read_syshugepages(const char *path, const char *node) {
   struct dirent *result;
   char path2[PATH_MAX];
   struct entry_info e_info;
-  long lim;
 
   dir = opendir(path);
   if (dir == NULL) {
@@ -168,18 +167,6 @@ static int read_syshugepages(const char *path, const char *node) {
     return -1;
   }
 
-  errno = 0;
-  if ((lim = pathconf(path, _PC_NAME_MAX)) == -1) {
-    /* Limit not defined if errno == 0, otherwise error */
-    if (errno != 0) {
-      ERROR("%s: pathconf failed", g_plugin_name);
-      closedir(dir);
-      return -1;
-    } else {
-      lim = PATH_MAX;
-    }
-  }
-
   /* read "hugepages-XXXXXkB" entries */
   while ((result = readdir(dir)) != NULL) {
     if (strncmp(result->d_name, hugepages_dir, sizeof(hugepages_dir) - 1)) {
@@ -189,7 +176,7 @@ static int read_syshugepages(const char *path, const char *node) {
     }
 
     /* /sys/devices/system/node/node?/hugepages/ */
-    ssnprintf(path2, (size_t)lim, "%s/%s", path, result->d_name);
+    ssnprintf(path2, sizeof(path2), "%s/%s", path, result->d_name);
 
     e_info.d_name = result->d_name;
     e_info.node = node;
@@ -216,7 +203,6 @@ static int read_nodes(void) {
   DIR *dir;
   struct dirent *result;
   char path[PATH_MAX];
-  long lim;
 
   dir = opendir(sys_node);
   if (dir == NULL) {
@@ -224,18 +210,6 @@ static int read_nodes(void) {
     return -1;
   }
 
-  errno = 0;
-  if ((lim = pathconf(sys_node, _PC_NAME_MAX)) == -1) {
-    /* Limit not defined if errno == 0, otherwise error */
-    if (errno != 0) {
-      ERROR("%s: pathconf failed", g_plugin_name);
-      closedir(dir);
-      return -1;
-    } else {
-      lim = PATH_MAX;
-    }
-  }
-
   while ((result = readdir(dir)) != NULL) {
     if (strncmp(result->d_name, node_string, sizeof(node_string) - 1)) {
       /* not node dir */
@@ -243,7 +217,7 @@ static int read_nodes(void) {
       continue;
     }
 
-    ssnprintf(path, (size_t)lim, sys_node_hugepages, result->d_name);
+    ssnprintf(path, sizeof(path), sys_node_hugepages, result->d_name);
     read_syshugepages(path, result->d_name);
     errno = 0;
   }