lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Message-ID: <20240116002731.216549-10-sashal@kernel.org>
Date: Mon, 15 Jan 2024 19:27:16 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>,
	David Howells <dhowells@...hat.com>,
	Marc Dionne <marc.dionne@...istor.com>,
	linux-afs@...ts.infradead.org,
	Sasha Levin <sashal@...nel.org>,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 10/12] rxrpc_find_service_conn_rcu: fix the usage of read_seqbegin_or_lock()

From: Oleg Nesterov <oleg@...hat.com>

[ Upstream commit bad1a11c0f061aa073bab785389fe04f19ba02e1 ]

rxrpc_find_service_conn_rcu() should make the "seq" counter odd on the
second pass, otherwise read_seqbegin_or_lock() never takes the lock.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Marc Dionne <marc.dionne@...istor.com>
cc: linux-afs@...ts.infradead.org
Link: https://lore.kernel.org/r/20231117164846.GA10410@redhat.com/
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/rxrpc/conn_service.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
index 21da48e3d2e5..7ad4b4e9341e 100644
--- a/net/rxrpc/conn_service.c
+++ b/net/rxrpc/conn_service.c
@@ -25,7 +25,7 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
 	struct rxrpc_conn_proto k;
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	struct rb_node *p;
-	unsigned int seq = 0;
+	unsigned int seq = 1;
 
 	k.epoch	= sp->hdr.epoch;
 	k.cid	= sp->hdr.cid & RXRPC_CIDMASK;
@@ -35,6 +35,7 @@ struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
 		 * under just the RCU read lock, so we have to check for
 		 * changes.
 		 */
+		seq++; /* 2 on the 1st/lockless path, otherwise odd */
 		read_seqbegin_or_lock(&peer->service_conn_lock, &seq);
 
 		p = rcu_dereference_raw(peer->service_conns.rb_node);
-- 
2.43.0


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ