From 19f1655fb5ee2283df0bebed54b9c2d208f5f555 Mon Sep 17 00:00:00 2001
From: tb <tb@openbsd.org>
Date: Tue, 9 Jun 2026 12:34:08 +0000
Subject: [PATCH] Avoid freeing a caller-owned buffer in PKCS7_verify()

If a PKCS#7 S/MIME message comes with an empty set of digestAlgorithms
in the SignedData, PKCS7_verify() would incorrectly free a caller-owned
buffer. Fix the freeing logic to avoid this situation.

From Igor Ustinov via OpenSSL
---
 lib/libcrypto/pkcs7/pk7_smime.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/lib/libcrypto/pkcs7/pk7_smime.c b/lib/libcrypto/pkcs7/pk7_smime.c
index 9baff7f5252..3806d170824 100644
--- a/lib/libcrypto/pkcs7/pk7_smime.c
+++ b/lib/libcrypto/pkcs7/pk7_smime.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pk7_smime.c,v 1.29 2025/12/20 07:22:43 tb Exp $ */
+/* $OpenBSD: pk7_smime.c,v 1.30 2026/06/09 12:34:08 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project.
  */
@@ -259,7 +259,7 @@ PKCS7_verify(PKCS7 *p7, STACK_OF(X509) *certs, X509_STORE *store, BIO *indata,
 	char buf[4096];
 	int i, j = 0, k, ret = 0;
 	BIO *p7bio;
-	BIO *tmpin, *tmpout;
+	BIO *next, *tmpin, *tmpout;
 
 	if (!p7) {
 		PKCS7error(PKCS7_R_INVALID_NULL_POINTER);
@@ -409,12 +409,12 @@ PKCS7_verify(PKCS7 *p7, STACK_OF(X509) *certs, X509_STORE *store, BIO *indata,
 
 	ret = 1;
 
-err:
-	if (tmpin == indata) {
-		if (indata)
-			BIO_pop(p7bio);
+ err:
+	while (p7bio != NULL && p7bio != indata) {
+		next = BIO_pop(p7bio);
+		BIO_free(p7bio);
+		p7bio = next;
 	}
-	BIO_free_all(p7bio);
 	sk_X509_free(signers);
 
 	return ret;