1 files changed, 18 insertions, 3 deletions

diff --git a/src/lib/libcrypto/bio/bio_lib.c b/src/lib/libcrypto/bio/bio_lib.c
index c09ad8fe8e..2ffa0a765c 100644
--- a/src/lib/libcrypto/bio/bio_lib.c
+++ b/src/lib/libcrypto/bio/bio_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bio_lib.c,v 1.39 2022/12/02 19:44:04 tb Exp $ */
+/* $OpenBSD: bio_lib.c,v 1.40 2022/12/06 16:10:55 schwarze Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -727,10 +727,25 @@ BIO_next(BIO *b)
         return b->next_bio;
 }
 
+/*
+ * Two chains "bio -> oldtail" and "oldhead -> next" become
+ * three chains "oldtail", "bio -> next", and "oldhead".
+ */
 void
-BIO_set_next(BIO *b, BIO *next)
+BIO_set_next(BIO *bio, BIO *next)
 {
-        b->next_bio = next;
+        /* Cut off the tail of the chain containing bio after bio. */
+        if (bio->next_bio != NULL)
+                bio->next_bio->prev_bio = NULL;
+
+        /* Cut off the head of the chain containing next before next. */
+        if (next != NULL && next->prev_bio != NULL)
+                next->prev_bio->next_bio = NULL;
+
+        /* Append the chain starting at next to the chain ending at bio. */
+        bio->next_bio = next;
+        if (next != NULL)
+                next->prev_bio = bio;
 }
 
 void