[PATCH net 4/4] rxrpc: Fix rxkad crypto unalignment handling

[David Howells <dhowells@redhat.com>]

Fix handling of a packet with a misaligned crypto length.  Also handle
non-ENOMEM errors from decryption by aborting.  Further, remove the
WARN_ON_ONCE() so that it can't be remotely triggered (a trace line can
still be emitted).

Fixes: f93af41b9f5f ("rxrpc: Fix missing error checks for rxkad encryption/decryption failure")
Closes: https://sashiko.dev/#/patchset/20260408121252.2249051-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
cc: stable@kernel.org
---
 include/trace/events/rxrpc.h | 1 +
 net/rxrpc/rxkad.c            | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 578b8038b211..5820d7e41ea0 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -37,6 +37,7 @@
 	EM(rxkad_abort_1_short_encdata,		"rxkad1-short-encdata")	\
 	EM(rxkad_abort_1_short_header,		"rxkad1-short-hdr")	\
 	EM(rxkad_abort_2_short_check,		"rxkad2-short-check")	\
+	EM(rxkad_abort_2_crypto_unaligned,	"rxkad2-crypto-unaligned") \
 	EM(rxkad_abort_2_short_data,		"rxkad2-short-data")	\
 	EM(rxkad_abort_2_short_header,		"rxkad2-short-hdr")	\
 	EM(rxkad_abort_2_short_len,		"rxkad2-short-len")	\
diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index 0acdc46f42c2..2c4697063ab2 100644
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -510,6 +510,9 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
 					  rxkad_abort_2_short_header);
 
+	/* Don't let the crypto algo see a misaligned length. */
+	sp->len = round_down(sp->len, 8);
+
 	/* Decrypt the skbuff in-place.  TODO: We really want to decrypt
 	 * directly into the target buffer.
 	 */
@@ -543,8 +546,10 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 	if (sg != _sg)
 		kfree(sg);
 	if (ret < 0) {
-		WARN_ON_ONCE(ret != -ENOMEM);
-		return ret;
+		if (ret == -ENOMEM)
+			return ret;
+		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
+					  rxkad_abort_2_crypto_unaligned);
 	}
 
 	/* Extract the decrypted packet length */