From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BE683A5E64 for ; Tue, 18 Aug 2026 16:27:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787070457; cv=none; b=OTD0FPoBBmHMtIxx6BQlh8XU1iy8Yh0nkJ4CbpTkIL70sGCHKsaOBTVvg8K/Mh7jwDAc6wWdeQeA67tTZc9RPV3p5sNqUhgLYVFX6lR/Eo70V2A+WrGvlbHDLdv9B9PQSDJWUP7thmpN1IHJFAlMfvmAFrQ6ypqzTyv97NlfINY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787070457; c=relaxed/simple; bh=ZkcoFqIICNvSNCcbNK41t7IVEVdpJ0/qEBYzuWoCQ0s=; h=From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type:Date; b=cmkh1nNCw4A8f97ZbWEp1hKAs8labHj//EKXiWSSTG1qVSnH6PV1SX8x3XcexgY3HgPF0soiyYG/IkoaZxQs6Gr8YlXBsxlnox+ll1S/q9n6OLJSedVx1+mcrAVP7eMWeCU1kwwhoiz3yqrV5qZ8Lf/8bxHd3iIcBx2X4xRHuCA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bu+UYJaA; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bu+UYJaA" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id D89861F000E9; Tue, 18 Aug 2026 16:27:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787070456; bh=alQEzlt7Wl16hOdSha/M8FC0uvbF5zGE8sK/vNnLJis=; h=From:To:Cc:Subject:Date; b=Bu+UYJaAVxxHWXK7mIaGCmXxDR8fcvvuYWKmdSsqNUxAmAU5C//qOxoWTA/D1WNjz lN+GCSjj15ofPj3BPQ88NIIMjiW0mfRFWkeeadlWEmnn4bwJ5Nbmsi54lu0gnU6PjR j47LOJD2K72pOBQke6vzHlw4WxZm+PO14bXkR6utSqGwQm9EwENI1PpCJ7Am5zuc03 YSY1ly2QFqdhPC+BPgsmbpOu+TOGYClwNN8mvVlYj6vxM2wXxc1I4yOQp36+w82vx3 p7WEXwNkEWfx3gGhTv4PG3UESehNEccwfYqaLq0nFWMmxFmJ1Oa+rn2fI0qlNH+pvb Zkq4OzjzxAO4g== From: "syzbot" To: syzkaller-upstream-moderation@googlegroups.com Cc: elver@google.com, syzbot@lists.linux.dev Subject: [PATCH RFC v2] rxrpc: Fix use-after-free in rxrpc_destroy_all_peers() Message-ID: <23b6e672-549a-4fd9-b731-9bfdc16148ea@mail.kernel.org> Precedence: bulk X-Mailing-List: syzbot@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Date: Tue, 18 Aug 2026 16:27:35 +0000 (UTC) During network namespace teardown, rxrpc_destroy_all_peers() iterates over the rxnet->peer_hash table to print leaked peers. However, it does so without holding rxnet->peer_hash_lock. This allows a race condition with asynchronous peer destruction, where RCU callbacks concurrently remove peers from the hash table and free them. When rxrpc_destroy_all_peers() accesses the freed peer, it results in a KASAN slab-use-after-free. BUG: KASAN: slab-use-after-free in rxrpc_destroy_all_peers+0xcc/0x150 net/rxrpc/peer_object.c:461 Read of size 8 at addr ffff88811089e420 by task kworker/u8:1/13 Call Trace: rxrpc_destroy_all_peers+0xcc/0x150 net/rxrpc/peer_object.c:461 rxrpc_exit_net+0x7f/0xc0 net/rxrpc/net_ns.c:114 ops_exit_list net/core/net_namespace.c:199 [inline] ops_undo_list+0x43d/0x8d0 net/core/net_namespace.c:252 cleanup_net+0x572/0x810 net/core/net_namespace.c:702 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0x92d/0xe10 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 To fix the slab-use-after-free, acquire rxnet->peer_hash_lock with spin_lock_bh() while iterating over rxnet->peer_hash in rxrpc_destroy_all_peers(). Additionally, insert rcu_barrier() in rxrpc_exit_net() prior to destroying peers and local endpoints. Without rcu_barrier(), rxrpc_destroy_all_peers() races with pending RCU callbacks that drop peer and local references, logging spurious leak warnings. Furthermore, this missing synchronization causes a downstream panic hazard in rxrpc_destroy_all_locals() because in-flight peer releases leave rxnet->local_endpoints populated. Calling rcu_barrier() ensures all pending RCU callbacks that drop peer and local references complete prior to leak checks and local endpoint destruction. Fixes: 17226f124038 ("rxrpc: Fix leak of rxrpc_peer objects") Assisted-by: Gemini:gemini-3.6-flash Gemini:gemini-3.1-pro-preview syzbot Reported-by: syzbot+c876adfab6362679008c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c876adfab6362679008c Link: https://syzkaller.appspot.com/ai_job?id=ca098ef4-2067-4197-977f-d5d409f27cb8 To: "David S. Miller" To: "David Howells" To: "Eric Dumazet" To: "Jakub Kicinski" To: To: "Marc Dionne" To: To: "Paolo Abeni" Cc: "Simon Horman" Cc: --- v2: - Added rcu_barrier() in rxrpc_exit_net() before peer and local endpoint teardown. - Updated commit message to detail how rcu_barrier() prevents spurious leak warnings and downstream panics in rxrpc_destroy_all_locals(). v1: https://lore.kernel.org/all/efbfa532-8931-4227-9ba4-701ac86a342e@mail.kernel.org/T/ --- diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c index 9a9834145..6895f51b7 100644 --- a/net/rxrpc/net_ns.c +++ b/net/rxrpc/net_ns.c @@ -111,6 +111,7 @@ static __net_exit void rxrpc_exit_net(struct net *net) timer_delete_sync(&rxnet->peer_keepalive_timer); rxrpc_destroy_all_calls(rxnet); rxrpc_destroy_all_connections(rxnet); + rcu_barrier(); rxrpc_destroy_all_peers(rxnet); rxrpc_destroy_all_locals(rxnet); proc_remove(rxnet->proc_net); diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c index fa9a406e1..d81ed180e 100644 --- a/net/rxrpc/peer_object.c +++ b/net/rxrpc/peer_object.c @@ -454,6 +454,8 @@ void rxrpc_destroy_all_peers(struct rxrpc_net *rxnet) struct rxrpc_peer *peer; int i; + spin_lock_bh(&rxnet->peer_hash_lock); + for (i = 0; i < HASH_SIZE(rxnet->peer_hash); i++) { if (hlist_empty(&rxnet->peer_hash[i])) continue; @@ -465,6 +467,8 @@ void rxrpc_destroy_all_peers(struct rxrpc_net *rxnet) &peer->srx.transport); } } + + spin_unlock_bh(&rxnet->peer_hash_lock); } /** base-commit: db2ddb87143519e20a95aa36c60b36107b736a58 -- This is an AI-generated patch subject to moderation. 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