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 12B27846A; Sat, 1 Aug 2026 08:51:55 +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=1785574317; cv=none; b=LqbjmbLwnxPKAZgSTiwmVgG5i8IT1tc7orz7ZX4fv8Zwdab98mCqIVxwsbePqXGKlcP5tEBozuq0kz4xZd9hmPVw1S63kPnye7PQ1UAQMJDsKu0zRchi8HSEb0B0jxnzdtV8F9alivUgzU6NyfoOszWaArFP0YyNdST/rjlc8+c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785574317; c=relaxed/simple; bh=J5DV9VvcBTHGZ6DCK3OSV2r8qVjUpJ5ye40RyKFKbnA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Qajyi0OeO7wKnPrtIwwh+pgMMiyjITTEXVIvOZyOKS/5OCRSL8TWO9KxQvS77Rd+AjxSTUEOMvQkzFruvb41RijkjC54uRFd0nwA1ueU4ql5TbN4HaMLokLIWbuk76WoLr50Twz9Ln5QQLSIFJUH/kDdLcBjMgbrC2qOUzv2HY8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VeERScBs; 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="VeERScBs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 899331F00ADE; Sat, 1 Aug 2026 08:51:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785574315; bh=2p4h7LgtBqZLcaXjtZmO6y8QdHjeUJC+/DixWNs6qa8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VeERScBsysEtOEmPrBuR5dCIAIPoaz7V+SdIv6hafa1WmlILw60X0/pzGnR7vv2Gm mX5JVc6YqYREmtcLiANWV203rQWNcLI76k/1uDUJEYod4KK9YvlF9gW/H0A+xRLBjK fCOiLanXUoUuuDOPRzIAWxygNyAGarWzZHWSedB6/F00gnzeLqUTHwDwftBd71GbOg QxGwmNC7YuEelTQxAMjn1rs3A4d2cAhWMH/Cc02fsmII7PWh1/JQBHZS87SvJgPFe1 7CeqqZZFJQlo81Lp+76kDKiW+jnwKzVp7MTrTasYeIRy3QpdYg8sZ7JTABlylk4UKg JfVINALo4GmFg== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 04/12] sched_ext: Reject internal enq_flags in the dsq move kfuncs Date: Fri, 31 Jul 2026 22:51:42 -1000 Message-ID: <20260801085150.2697653-5-tj@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260801085150.2697653-1-tj@kernel.org> References: <20260801085150.2697653-1-tj@kernel.org> Precedence: bulk X-Mailing-List: sched-ext@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The dsq insert kfuncs reject __SCX_ENQ_INTERNAL_MASK bits in scx_dsq_insert_preamble() instead of scx_vet_enq_flags(). A scheduler can smuggle internal flags such as SCX_ENQ_CLEAR_OPSS through the dsq move kfuncs and corrupt the dispatch protocol. Move the rejection into scx_vet_enq_flags(). The vtime move wrapper OR'd the internal SCX_ENQ_DSQ_PRIQ bit into enq_flags before the vet; the bit now goes in inside scx_dsq_move() after the vet. Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 9ce7e50c13d3..028cfbcd1314 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -8393,6 +8393,11 @@ static bool scx_vet_enq_flags(struct scx_sched *sch, u64 dsq_id, u64 *enq_flags) bool is_local = dsq_id == SCX_DSQ_LOCAL || (dsq_id & SCX_DSQ_LOCAL_ON) == SCX_DSQ_LOCAL_ON; + if (unlikely(*enq_flags & __SCX_ENQ_INTERNAL_MASK)) { + scx_error(sch, "invalid enq_flags 0x%llx", *enq_flags); + return false; + } + if (*enq_flags & SCX_ENQ_IMMED) { if (unlikely(!is_local)) { scx_error(sch, "SCX_ENQ_IMMED on a non-local DSQ 0x%llx", dsq_id); @@ -8415,11 +8420,6 @@ static bool scx_dsq_insert_preamble(struct scx_sched *sch, struct task_struct *p return false; } - if (unlikely(*enq_flags & __SCX_ENQ_INTERNAL_MASK)) { - scx_error(sch, "invalid enq_flags 0x%llx", *enq_flags); - return false; - } - /* see SCX_EV_INSERT_NOT_OWNED definition */ if (unlikely(!scx_task_on_sched(sch, p))) { __scx_add_event(sch, SCX_EV_INSERT_NOT_OWNED, 1); @@ -8651,7 +8651,8 @@ static const struct btf_kfunc_id_set scx_kfunc_set_enqueue_dispatch = { }; static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit, - struct task_struct *p, u64 dsq_id, u64 enq_flags) + struct task_struct *p, u64 dsq_id, u64 enq_flags, + bool priq) { struct scx_dispatch_q *src_dsq = kit->dsq, *dst_dsq; struct scx_sched *sch; @@ -8673,6 +8674,10 @@ static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit, if (!scx_vet_enq_flags(sch, dsq_id, &enq_flags)) return false; + /* internal bit, can only go in after @enq_flags is vetted */ + if (priq) + enq_flags |= SCX_ENQ_DSQ_PRIQ; + /* * If the BPF scheduler keeps calling this function repeatedly, it can * cause similar live-lock conditions as scx_consume_dispatch_q(). @@ -8929,7 +8934,7 @@ __bpf_kfunc bool scx_bpf_dsq_move(struct bpf_iter_scx_dsq *it__iter, u64 enq_flags) { return scx_dsq_move((struct bpf_iter_scx_dsq_kern *)it__iter, - p, dsq_id, enq_flags); + p, dsq_id, enq_flags, false); } /** @@ -8954,7 +8959,7 @@ __bpf_kfunc bool scx_bpf_dsq_move_vtime(struct bpf_iter_scx_dsq *it__iter, u64 enq_flags) { return scx_dsq_move((struct bpf_iter_scx_dsq_kern *)it__iter, - p, dsq_id, enq_flags | SCX_ENQ_DSQ_PRIQ); + p, dsq_id, enq_flags, true); } __bpf_kfunc_end_defs(); -- 2.55.0