follow symlinks to find the true passwd file before updating.

1 files changed, 6 insertions, 1 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index 388adf81f..e99db40c0 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -52,6 +52,10 @@ int update_passwd(const char *filename, const char *username,
         int cnt = 0;
         int ret = -1; /* failure */
 
+        filename = xmalloc_readlink_follow(filename);
+        if (filename == NULL)
+                return -1;
+
         check_selinux_update_passwd(username);
 
         /* New passwd file, "/etc/passwd+" for now */
@@ -143,6 +147,7 @@ int update_passwd(const char *filename, const char *username,
 
  free_mem:
         free(fnamesfx);
-        free((char*)username);
+        free((char *)filename);
+        free((char *)username);
         return ret;
 }