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 d3c12e7fda36a28592154902637ab7b3b70e6df0..c4ab2d6c714340f674eacac03315db97b5468d25 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);
 }
 
 /*