Check for existing dso in LD_PRELOAD and only add it if it is not

already present.

diff --git a/src/exec_common.c b/src/exec_common.c
index fefbce8996dc9c66307be5540f72119b54efd6d0..20b5df6c7121b523025337b245799d6d47f438e2 100644 (file)
--- a/src/exec_common.c
+++ b/src/exec_common.c
@@ -46,6 +46,7 @@ preload_dso(char *envp[], const char *dso_file)
     char *preload = NULL;
     int env_len;
     int preload_idx = -1;
+    bool present = false;
 # ifdef RTLD_PRELOAD_ENABLE_VAR
     bool enabled = false;
 # else
@@ -61,7 +62,27 @@ preload_dso(char *envp[], const char *dso_file)
 
     /* Count entries in envp, looking for LD_PRELOAD as we go. */
     for (env_len = 0; envp[env_len] != NULL; env_len++) {
-       if (strncmp(envp[env_len], RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
+       if (preload_idx == -1 && strncmp(envp[env_len], RTLD_PRELOAD_VAR "=",
+           sizeof(RTLD_PRELOAD_VAR)) == 0) {
+           const char *cp = envp[env_len] + sizeof(RTLD_PRELOAD_VAR);
+           const char *end = cp + strlen(cp);
+           const char *ep;
+           const size_t dso_len = strlen(dso_file);
+
+           /* Check to see if dso_file is already present. */
+           for (cp = sudo_strsplit(cp, end, RTLD_PRELOAD_DELIM, &ep);
+               cp != NULL; cp = sudo_strsplit(NULL, end, RTLD_PRELOAD_DELIM,
+               &ep)) {
+               if ((size_t)(ep - cp) == dso_len) {
+                   if (memcmp(cp, dso_file, dso_len) == 0) {
+                       /* already present */
+                       present = true;
+                       break;
+                   }
+               }
+           }
+
+           /* Save index of existing LD_PRELOAD variable. */
            preload_idx = env_len;
            continue;
        }
@@ -90,23 +111,29 @@ preload_dso(char *envp[], const char *dso_file)
     }
 
     /* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
-    if (preload_idx == -1) {
+    if (!present) {
+       if (preload_idx == -1) {
 # ifdef RTLD_PRELOAD_DEFAULT
-       asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, dso_file,
-           RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
+           asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, dso_file,
+               RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
 # else
-       preload = sudo_new_key_val(RTLD_PRELOAD_VAR, dso_file);
+           preload = sudo_new_key_val(RTLD_PRELOAD_VAR, dso_file);
 # endif
-       if (preload == NULL)
-           sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-       envp[env_len++] = preload;
-       envp[env_len] = NULL;
-    } else {
-       int len = asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR,
-           dso_file, RTLD_PRELOAD_DELIM, envp[preload_idx]);
-       if (len == -1)
-           sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-       envp[preload_idx] = preload;
+           if (preload == NULL) {
+               sudo_fatalx(U_("%s: %s"), __func__,
+                   U_("unable to allocate memory"));
+           }
+           envp[env_len++] = preload;
+           envp[env_len] = NULL;
+       } else {
+           int len = asprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR,
+               dso_file, RTLD_PRELOAD_DELIM, envp[preload_idx]);
+           if (len == -1) {
+               sudo_fatalx(U_("%s: %s"), __func__,
+                   U_("unable to allocate memory"));
+           }
+           envp[preload_idx] = preload;
+       }
     }
 # ifdef RTLD_PRELOAD_ENABLE_VAR
     if (!enabled) {