gconv: Check reference count in __gconv_release_cache [BZ #24677]

This fixes a regression introduced in commit
7e740ab2e7be7d83b75513aa406e0b10875f7f9c ("libio: Fix gconv-related
memory leak [BZ #24583]").

__gconv_release_cache is only ever called with heap-allocated
arrays which contain at least one member.  The statically allocated
ASCII steps are filtered out by __wcsmbs_close_conv.

1 files changed, 6 insertions, 3 deletions

diff --git a/iconv/gconv_cache.c b/iconv/gconv_cache.c
index 9a456bf825..4db7287cee 100644
--- a/iconv/gconv_cache.c
+++ b/iconv/gconv_cache.c
@@ -446,9 +446,12 @@ __gconv_lookup_cache (const char *toset, const char *fromset,
 void
 __gconv_release_cache (struct __gconv_step *steps, size_t nsteps)
 {
-  if (gconv_cache != NULL)
-    /* The only thing we have to deallocate is the record with the
-       steps.  */
+  /* The only thing we have to deallocate is the record with the
+     steps.  But do not do this if the reference counter is still
+     positive.  This can happen if the steps array was cloned by
+     __wcsmbs_clone_conv.  (The array elements have separate __counter
+     fields, but they are only out of sync temporarily.)  */
+  if (gconv_cache != NULL && steps->__counter == 0)
     free (steps);
 }