pgcrypto: avoid recursive ResourceOwnerForget().

Raising an error within a function using an OSSLCipher object led
to a complaint from ResourceOwnerForget and then a double-free crash,
because ResOwnerReleaseOSSLCipher forgot to unhook the OSSLCipher
object from its owner.  (The sibling logic for OSSLDigest objects got
this right, as did every other ReleaseResource function AFAICS.)

Oversight in cd694f60d.

Bug: #19527
Reported-by: Yuelin Wang <3020001251@tju.edu.cn>
Author: Yuelin Wang <3020001251@tju.edu.cn>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19527-6e7686960c6dce78@postgresql.org
Backpatch-through: 17

diff --git a/contrib/pgcrypto/openssl.c b/contrib/pgcrypto/openssl.c
index f179e80c8429ec00bbbcd7feae298652f16f976a..51f28799a41348a421033b2d8307e64c5a2015ff 100644 (file)
--- a/contrib/pgcrypto/openssl.c
+++ b/contrib/pgcrypto/openssl.c
@@ -832,7 +832,10 @@ px_find_cipher(const char *name, PX_Cipher **res)
 static void
 ResOwnerReleaseOSSLCipher(Datum res)
 {
-       free_openssl_cipher((OSSLCipher *) DatumGetPointer(res));
+       OSSLCipher *cipher = (OSSLCipher *) DatumGetPointer(res);
+
+       cipher->owner = NULL;
+       free_openssl_cipher(cipher);
 }
 
 /*