More accurate max env size detection in env_mergen

Signed-off-by: Laurent Bercot <ska@appnovation.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/src/libenvexec/env_mergen.c b/src/libenvexec/env_mergen.c
index acc7c39..64a77cb 100644
--- a/src/libenvexec/env_mergen.c
+++ b/src/libenvexec/env_mergen.c
@@ -10,7 +10,7 @@ size_t env_mergen (char const **v, size_t vmax, char const *const *envp, size_t
 {
   size_t vlen = envlen ;
   size_t i = 0 ;
-  if (envlen + n + 1 > vmax) return (errno = ENAMETOOLONG, 0) ;
+  if (envlen >= vmax) return 0 ;
   for (; i < envlen ; i++) v[i] = envp[i] ;
   for (i = 0 ; i < modiflen ; i += strlen(modifs + i) + 1)
   {
@@ -19,8 +19,13 @@ size_t env_mergen (char const **v, size_t vmax, char const *const *envp, size_t
     for (; j < vlen ; j++)
       if (!strncmp(modifs + i, v[j], split) && (v[j][split] == '=')) break ;
     if (j < vlen) v[j] = v[--vlen] ;
-    if (modifs[i + split]) v[vlen++] = modifs + i ;
+    if (modifs[i + split])
+    {
+      if (vlen >= vmax) return 0 ;
+      v[vlen++] = modifs + i ;
+    }
   }
+  if (vlen >= vmax) return 0 ;
   v[vlen++] = 0 ;
   return vlen ;
 }