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

1 files changed, 7 insertions, 7 deletions

diff --git a/src/lib/libcrypto/pkcs7/pk7_smime.c b/src/lib/libcrypto/pkcs7/pk7_smime.c
index 9baff7f525..3806d17082 100644
--- a/src/lib/libcrypto/pkcs7/pk7_smime.c
+++ b/src/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;