From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 33DFA3FBEDD; Fri, 24 Apr 2026 20:44:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777063462; cv=none; b=tuOZD+xdZvX+Y7ZG+zY6X/yLxzAibGxd4RMWYjyWm2O7FznSUG0pEcq8Txx8yWz8YpsBHVcCqXxu2i1NEPS+qc8n2vcU8teG/xdCJgmSGsExwrLyTDSd7Wx4qzXDV8thjOIu/YmNjVERmc1E0TTQzC8GG+FG42fZC+NJ9ws+5zY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777063462; c=relaxed/simple; bh=4zgA/8D5i8VIk2iiuAZijpdOo+YcCOiQlUoXstiK0x8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EIi3JhhBCIsta0RzLLjEcx9Sn//c9Ox99q9p8ps65f+RRMqKdC0WuC1ymimvdLpuhyRJDdLRsRE/mjQlXG5bS5Yn6Ubs6EUpmEeI3pR+f7A5mthThzeC1qRdKHBL1V1GxjaJAE6QGRrVnYANKKBVDff11HlHgI/QbEo/tw+XqLk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uyWJ9R1B; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uyWJ9R1B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF12FC2BCB0; Fri, 24 Apr 2026 20:44:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777063462; bh=4zgA/8D5i8VIk2iiuAZijpdOo+YcCOiQlUoXstiK0x8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uyWJ9R1B+AWZ5TyRrDDy+uH1L7QK+ou0w1yaZ2vGWnjqAr+4aPTatYfWaivS60dFY JUxsro0O85EBB/XRFuDZWvO9OH2BIwdUhktV0j32VQJmLKqdUXL1vR4FJdBa9VX2vm HyfJaJm+nqX9U27J9iRSeBprxZj6swLjd3OjB6VPZH62cAfweQjL1r9egtiMDFrc8V GuSlbtl0iG8z4i0SAgmNbANMmSPAoIzV3LlX8EkG3T1KkgLFq9YwfGivm7Wd4OSnbH zZqHhEzJLXp5wpVOAHJMmaBVsf2tNgqYstH3eIbG+2kflshFmEBR0ak3XEN1IyG+jp 9122HFW++nlkg== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Emil Tsalapatis , Chris Mason , Ryan Newton , Tejun Heo , stable@vger.kernel.org Subject: [PATCH 02/13] sched_ext: Guard scx_dsq_move() against NULL kit->dsq after failed iter_new Date: Fri, 24 Apr 2026 10:44:07 -1000 Message-ID: <20260424204418.3809733-3-tj@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424204418.3809733-1-tj@kernel.org> References: <20260424204418.3809733-1-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_iter_scx_dsq_new() clears kit->dsq on failure and bpf_iter_scx_dsq_{next,destroy}() guard against that. scx_dsq_move() doesn't - it dereferences kit->dsq immediately, so a BPF program that calls scx_bpf_dsq_move[_vtime]() after a failed iter_new oopses the kernel. Return false if kit->dsq is NULL. Fixes: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()") Cc: stable@vger.kernel.org # v6.12+ Reported-by: Chris Mason Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 0c435a4612dc..89170a0e5779 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -8055,12 +8055,22 @@ static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit, struct task_struct *p, u64 dsq_id, u64 enq_flags) { struct scx_dispatch_q *src_dsq = kit->dsq, *dst_dsq; - struct scx_sched *sch = src_dsq->sched; + struct scx_sched *sch; struct rq *this_rq, *src_rq, *locked_rq; bool dispatched = false; bool in_balance; unsigned long flags; + /* + * The verifier considers an iterator slot initialized on any + * KF_ITER_NEW return, so a BPF program may legally reach here after + * bpf_iter_scx_dsq_new() failed and left @kit->dsq NULL. + */ + if (unlikely(!src_dsq)) + return false; + + sch = src_dsq->sched; + if (!scx_vet_enq_flags(sch, dsq_id, &enq_flags)) return false; -- 2.53.0