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 DC9BE1822CD; Wed, 3 Jul 2024 10:54:20 +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=1720004061; cv=none; b=OnTLjpGshjLosgnOtcbb+kAF0im9c1bCFTrGCPhZZtxbfD/mCYtMhsQuCi/JySuZ2YtqvxDFogViJEbYwV2mkjTHC73N7TJkxz9OFSMYvwfbjrep+FkYsbHQhkHlxDu+BvA5UAF0OvQBPL1FcRM9uWzOuno9coVbvROloxtTwJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720004061; c=relaxed/simple; bh=F03cmPFnIXXL0WksFqvtTv9RDzU4Gt/udtrBvJqBlZw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pFfQot56QBFEWmY5WJy2j9ca21ZW+WO0sce1MhiWc67MaK4mPb3BULvkaQ7F4Fk3lel3O/m9kxv2c6ndnCfGI1hKgutbC7sqTDVGrmGd0KdYU3bJkY0CURrENLDtDAAbA1PlMtkP8RAU4btzCSD7082qPtUzG+LAuzvqEDZ4jVo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2LUCKhXq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2LUCKhXq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28837C2BD10; Wed, 3 Jul 2024 10:54:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720004060; bh=F03cmPFnIXXL0WksFqvtTv9RDzU4Gt/udtrBvJqBlZw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2LUCKhXqWIQA5bUSf+Xtw5t3yK4r3gxMyYlCHxNpOz/If0Aaxk49uaBsPvIeEKu2V 7azO0PX4joZXXYbjpu4JE3QS4CxrcgJyrFIA9VWRkXqwQ09RlMgzqcNyloYeWpwrDM YJ2x4DpCaKxjTpTmqVoecFcwShAzY1M2IsRnjBtQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+b87c222546179f4513a7@syzkaller.appspotmail.com, David Ruth , Jamal Hadi Salim , Paolo Abeni , Sasha Levin Subject: [PATCH 5.4 110/189] net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc() Date: Wed, 3 Jul 2024 12:39:31 +0200 Message-ID: <20240703102845.653116532@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102841.492044697@linuxfoundation.org> References: <20240703102841.492044697@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Ruth [ Upstream commit d864319871b05fadd153e0aede4811ca7008f5d6 ] syzbot found hanging tasks waiting on rtnl_lock [1] A reproducer is available in the syzbot bug. When a request to add multiple actions with the same index is sent, the second request will block forever on the first request. This holds rtnl_lock, and causes tasks to hang. Return -EAGAIN to prevent infinite looping, while keeping documented behavior. [1] INFO: task kworker/1:0:5088 blocked for more than 143 seconds. Not tainted 6.9.0-rc4-syzkaller-00173-g3cdb45594619 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:0 state:D stack:23744 pid:5088 tgid:5088 ppid:2 flags:0x00004000 Workqueue: events_power_efficient reg_check_chans_work Call Trace: context_switch kernel/sched/core.c:5409 [inline] __schedule+0xf15/0x5d00 kernel/sched/core.c:6746 __schedule_loop kernel/sched/core.c:6823 [inline] schedule+0xe7/0x350 kernel/sched/core.c:6838 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6895 __mutex_lock_common kernel/locking/mutex.c:684 [inline] __mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752 wiphy_lock include/net/cfg80211.h:5953 [inline] reg_leave_invalid_chans net/wireless/reg.c:2466 [inline] reg_check_chans_work+0x10a/0x10e0 net/wireless/reg.c:2481 Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action") Reported-by: syzbot+b87c222546179f4513a7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b87c222546179f4513a7 Signed-off-by: David Ruth Reviewed-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20240614190326.1349786-1-druth@chromium.org Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/sched/act_api.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 92477d51c49dd..52394e45bac55 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -493,7 +493,6 @@ int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index, u32 max; if (*index) { -again: rcu_read_lock(); p = idr_find(&idrinfo->action_idr, *index); @@ -502,7 +501,7 @@ int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index, * index but did not assign the pointer yet. */ rcu_read_unlock(); - goto again; + return -EAGAIN; } if (!p) { -- 2.43.0