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 6027B9443 for ; Sun, 13 Aug 2023 21:23:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0A37C433C9; Sun, 13 Aug 2023 21:23:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691961788; bh=e359yJop2fp5uwsKmsGRxJqrc8tJ3j6u1dUOUgmEzvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0k4ixmmmbNkdwR1IPqzDFV4DOE33II/vDTmKuvmXrl7McJgXZME3bp2ip9MpwnmEj Xjobki8Gs9jBORgXflq8O7hqBeqh12Tkjv3aqFwyrxYPTM5CoJ2NdRkaxAMkBlhw9c FavOCgW3uwLl/iWzhmIoPEiDDaJcxscidon1LroQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Eric Dumazet , Stephen Hemminger , Jamal Hadi Salim , Simon Horman , Jakub Kicinski , Fedor Pchelkin Subject: [PATCH 4.19 33/33] sch_netem: fix issues in netem_change() vs get_dist_table() Date: Sun, 13 Aug 2023 23:19:27 +0200 Message-ID: <20230813211705.141126984@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230813211703.915807095@linuxfoundation.org> References: <20230813211703.915807095@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Eric Dumazet commit 11b73313c12403f617b47752db0ab3deef201af7 upstream. In blamed commit, I missed that get_dist_table() was allocating memory using GFP_KERNEL, and acquiring qdisc lock to perform the swap of newly allocated table with current one. In this patch, get_dist_table() is allocating memory and copy user data before we acquire the qdisc lock. Then we perform swap operations while being protected by the lock. Note that after this patch netem_change() no longer can do partial changes. If an error is returned, qdisc conf is left unchanged. Fixes: 2174a08db80d ("sch_netem: acquire qdisc lock in netem_change()") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Stephen Hemminger Acked-by: Jamal Hadi Salim Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20230622181503.2327695-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Fedor Pchelkin Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_netem.c | 59 +++++++++++++++++++++----------------------------- 1 file changed, 25 insertions(+), 34 deletions(-) --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -748,12 +748,10 @@ static void dist_free(struct disttable * * signed 16 bit values. */ -static int get_dist_table(struct Qdisc *sch, struct disttable **tbl, - const struct nlattr *attr) +static int get_dist_table(struct disttable **tbl, const struct nlattr *attr) { size_t n = nla_len(attr)/sizeof(__s16); const __s16 *data = nla_data(attr); - spinlock_t *root_lock; struct disttable *d; int i; @@ -768,13 +766,7 @@ static int get_dist_table(struct Qdisc * for (i = 0; i < n; i++) d->table[i] = data[i]; - root_lock = qdisc_root_sleeping_lock(sch); - - spin_lock_bh(root_lock); - swap(*tbl, d); - spin_unlock_bh(root_lock); - - dist_free(d); + *tbl = d; return 0; } @@ -930,6 +922,8 @@ static int netem_change(struct Qdisc *sc { struct netem_sched_data *q = qdisc_priv(sch); struct nlattr *tb[TCA_NETEM_MAX + 1]; + struct disttable *delay_dist = NULL; + struct disttable *slot_dist = NULL; struct tc_netem_qopt *qopt; struct clgstate old_clg; int old_loss_model = CLG_RANDOM; @@ -943,6 +937,18 @@ static int netem_change(struct Qdisc *sc if (ret < 0) return ret; + if (tb[TCA_NETEM_DELAY_DIST]) { + ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]); + if (ret) + goto table_free; + } + + if (tb[TCA_NETEM_SLOT_DIST]) { + ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]); + if (ret) + goto table_free; + } + sch_tree_lock(sch); /* backup q->clg and q->loss_model */ old_clg = q->clg; @@ -952,26 +958,17 @@ static int netem_change(struct Qdisc *sc ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]); if (ret) { q->loss_model = old_loss_model; + q->clg = old_clg; goto unlock; } } else { q->loss_model = CLG_RANDOM; } - if (tb[TCA_NETEM_DELAY_DIST]) { - ret = get_dist_table(sch, &q->delay_dist, - tb[TCA_NETEM_DELAY_DIST]); - if (ret) - goto get_table_failure; - } - - if (tb[TCA_NETEM_SLOT_DIST]) { - ret = get_dist_table(sch, &q->slot_dist, - tb[TCA_NETEM_SLOT_DIST]); - if (ret) - goto get_table_failure; - } - + if (delay_dist) + swap(q->delay_dist, delay_dist); + if (slot_dist) + swap(q->slot_dist, slot_dist); sch->limit = qopt->limit; q->latency = PSCHED_TICKS2NS(qopt->latency); @@ -1021,17 +1018,11 @@ static int netem_change(struct Qdisc *sc unlock: sch_tree_unlock(sch); - return ret; -get_table_failure: - /* recover clg and loss_model, in case of - * q->clg and q->loss_model were modified - * in get_loss_clg() - */ - q->clg = old_clg; - q->loss_model = old_loss_model; - - goto unlock; +table_free: + dist_free(delay_dist); + dist_free(slot_dist); + return ret; } static int netem_init(struct Qdisc *sch, struct nlattr *opt,