[PATCH 6.12.y] rxrpc: Fix key quota calculation for multitoken keys

[Sasha Levin]

From: David Howells <dhowells at redhat.com>

[ Upstream commit bdbfead6d38979475df0c2f4bad2b19394fe9bdc ]

In the rxrpc key preparsing, every token extracted sets the proposed quota
value, but for multitoken keys, this will overwrite the previous proposed
quota, losing it.

Fix this by adding to the proposed quota instead.

Fixes: 8a7a3eb4ddbe ("KEYS: RxRPC: Use key preparsing")
Closes: https://sashiko.dev/#/patchset/20260319150150.4189381-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells at redhat.com>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: Jeffrey Altman <jaltman at auristor.com>
cc: Simon Horman <horms at kernel.org>
cc: linux-afs at lists.infradead.org
cc: stable at kernel.org
Link: https://patch.msgid.link/20260408121252.2249051-2-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
[ dropped hunk for rxrpc_preparse_xdr_yfs_rxgk() ]
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 net/rxrpc/key.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
index 33e8302a79e33..215e661676381 100644
--- a/net/rxrpc/key.c
+++ b/net/rxrpc/key.c
@@ -72,7 +72,7 @@ static int rxrpc_preparse_xdr_rxkad(struct key_preparsed_payload *prep,
 		return -EKEYREJECTED;
 
 	plen = sizeof(*token) + sizeof(*token->kad) + tktlen;
-	prep->quotalen = datalen + plen;
+	prep->quotalen += datalen + plen;
 
 	plen -= sizeof(*token);
 	token = kzalloc(sizeof(*token), GFP_KERNEL);
@@ -303,6 +303,7 @@ static int rxrpc_preparse(struct key_preparsed_payload *prep)
 	memcpy(&kver, prep->data, sizeof(kver));
 	prep->data += sizeof(kver);
 	prep->datalen -= sizeof(kver);
+	prep->quotalen = 0;
 
 	_debug("KEY I/F VERSION: %u", kver);
 
@@ -340,7 +341,7 @@ static int rxrpc_preparse(struct key_preparsed_payload *prep)
 		goto error;
 
 	plen = sizeof(*token->kad) + v1->ticket_length;
-	prep->quotalen = plen + sizeof(*token);
+	prep->quotalen += plen + sizeof(*token);
 
 	ret = -ENOMEM;
 	token = kzalloc(sizeof(*token), GFP_KERNEL);
-- 
2.53.0