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 2662611C83 for ; Mon, 28 Aug 2023 10:29:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E452C433C7; Mon, 28 Aug 2023 10:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693218563; bh=gsVMPNCM3Lk9Ztpj4B8O6vQ/0R5AhsNyTiCR4iCFVM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hZs7sEOQNz3CRrNFxWfyyzruRKQmZ2fvqAvTi8FOU9TG7cDbJP/6KTuqe+iBeQfeo K5XJNijVA6z7nYX8PeAXyOrecIO8td/etAav3HBiIkuRbatKYmltE1iydozgHbzQCY 1Fhp0WUhRqXPCIZAsBdTiEIlfHpKHcJ6pAd17Rqc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pietro Borrello , "Peter Zijlstra (Intel)" , Phil Auld , "Steven Rostedt (Google)" , Sasha Levin , Srish Srinivasan Subject: [PATCH 4.19 122/129] sched/rt: pick_next_rt_entity(): check list_entry Date: Mon, 28 Aug 2023 12:13:36 +0200 Message-ID: <20230828101157.667792677@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230828101153.030066927@linuxfoundation.org> References: <20230828101153.030066927@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pietro Borrello commit 7c4a5b89a0b5a57a64b601775b296abf77a9fe97 upstream. Commit 326587b84078 ("sched: fix goto retry in pick_next_task_rt()") removed any path which could make pick_next_rt_entity() return NULL. However, BUG_ON(!rt_se) in _pick_next_task_rt() (the only caller of pick_next_rt_entity()) still checks the error condition, which can never happen, since list_entry() never returns NULL. Remove the BUG_ON check, and instead emit a warning in the only possible error condition here: the queue being empty which should never happen. Fixes: 326587b84078 ("sched: fix goto retry in pick_next_task_rt()") Signed-off-by: Pietro Borrello Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Phil Auld Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20230128-list-entry-null-check-sched-v3-1-b1a71bd1ac6b@diag.uniroma1.it Signed-off-by: Sasha Levin [ Fixes CVE-2023-1077: sched/rt: pick_next_rt_entity(): check list_entry An insufficient list empty checking in pick_next_rt_entity(). The _pick_next_task_rt() checks pick_next_rt_entity() returns NULL or not but pick_next_rt_entity() never returns NULL. So, even if the list is empty, _pick_next_task_rt() continues its process. ] Signed-off-by: Srish Srinivasan Signed-off-by: Greg Kroah-Hartman --- kernel/sched/rt.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1522,6 +1522,8 @@ static struct sched_rt_entity *pick_next BUG_ON(idx >= MAX_RT_PRIO); queue = array->queue + idx; + if (SCHED_WARN_ON(list_empty(queue))) + return NULL; next = list_entry(queue->next, struct sched_rt_entity, run_list); return next; @@ -1535,7 +1537,8 @@ static struct task_struct *_pick_next_ta do { rt_se = pick_next_rt_entity(rq, rt_rq); - BUG_ON(!rt_se); + if (unlikely(!rt_se)) + return NULL; rt_rq = group_rt_rq(rt_se); } while (rt_rq);