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 E908537DEBA; Mon, 11 May 2026 22:03:36 +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=1778537017; cv=none; b=WVKLpMp0HRNy+qVuDwMHZUSrhjc2y9yH+GjYHmL6PVdRCZp6yeYqAu8tG6f2JPGGJ/Sf6RJOUCD1rOyNzqjyFAdHbygtdY5Zs1/vLmvpeaqavmCESaXDRrBHKEAHKTQB/ZxwSzEzLnScZMkHVuI5FfcJfzm12arFXCDRXtsjKmI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778537017; c=relaxed/simple; bh=KyEdPWkVvJVcl3kwEFMfGF/vIvoJQ1RgxyA8hNrUA4c=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=BJTRisOz3ggnh8H+3WeMaFZgoQfACdQ9o0P2Q8zayJuwHuZ09W+P8kqjJgt9ene5WgBaEUdru20C1Oa9tLt9TjNNjQ06c428zP6b1i+PZbfhXqHH1WFL/4mrUiIoIHn2ZtofYgg2eJgU+TJ3rGDi+2RTrebDXzQkoNxnWhinO2U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VE+KjpMv; 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="VE+KjpMv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 818EBC2BCB0; Mon, 11 May 2026 22:03:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778537016; bh=KyEdPWkVvJVcl3kwEFMfGF/vIvoJQ1RgxyA8hNrUA4c=; h=From:To:Cc:Subject:Date:From; b=VE+KjpMvPO6vnI7xcSvmeadyzHaP6L8qb20Qwuj16DTc78YSIS4TUTp3hsYpKPtX+ CW5xWJfmNtOF+uK9b8iwImE+P0g9je51DWvqhu8aI33ONjCj5yRyck2hz6XEnbOAkt Hwya+3puOaHFPTdG7sMEsqcv3yZZr98ZKS2onfNZSC2Kwrf5JDC7Sritij1woIdNd3 uSeYU1rZAdrwlGvz7NURRSK99Hs9NqHbUwEGlrFh9XCPPBjBWC0yuZsvOE6v6rl6RN KWVBE90gRQdC/cxY5J846GTcD4VdcUpWwGnslsvfs1Pa9ThLPwYwWxgfEcSVyg9FCI 0aSLaS1K7enrQ== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev Cc: Emil Tsalapatis , linux-kernel@vger.kernel.org, Sashiko , Tejun Heo , stable@vger.kernel.org Subject: [PATCH sched_ext/for-7.1-fixes] sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path Date: Mon, 11 May 2026 12:03:35 -1000 Message-ID: <20260511220335.144621-1-tj@kernel.org> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In scx_root_enable_workfn(), put_task_struct(p) is called before scx_error() dereferences p->comm and p->pid. If the iterator's reference is the last drop, the task is freed synchronously and the deref becomes a UAF. Move put_task_struct() past scx_error(). Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260511214031.AF5E9C2BCB0@smtp.kernel.org/ Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 1efd5d82b08b..9354da79e162 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6973,10 +6973,10 @@ static void scx_root_enable_workfn(struct kthread_work *work) if (scx_get_task_state(p) != SCX_TASK_DEAD) scx_set_task_state(p, SCX_TASK_NONE); task_rq_unlock(rq, p, &rf); - put_task_struct(p); scx_task_iter_stop(&sti); scx_error(sch, "ops.init_task() failed (%d) for %s[%d]", ret, p->comm, p->pid); + put_task_struct(p); goto err_disable_unlock_all; } -- 2.49.1