From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 554033B2A4 for ; Mon, 6 Jan 2025 08:40:06 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736170806; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=Aykk49gbvca+fRkPZSvRtNtvxhZhBnfZrlAGzlCj8GE=; b=Gdg9KAh/BH76bFiJc1V+usgGNka5NJwK44WzZgzHRU3gjX5FX91bBk4DX4vgG48vaW8h3i 2J2m6UhrhllI2A2zr3Q7/fJMGoha6f1GVgW5n/8TW1pPDbXJDD5lZSzv2VO7OJkupbT2WA GgNT/DrVxhEVTNAEyL+9K4aoaZSVnuc= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-120-75_BDC4pPwCWzeBKq5jxTQ-1; Mon, 06 Jan 2025 08:40:04 -0500 X-MC-Unique: 75_BDC4pPwCWzeBKq5jxTQ-1 X-Mimecast-MFC-AGG-ID: 75_BDC4pPwCWzeBKq5jxTQ Received: by mail-ej1-f72.google.com with SMTP id a640c23a62f3a-aa68952272bso196161166b.2 for ; Mon, 06 Jan 2025 05:40:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736170803; x=1736775603; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Aykk49gbvca+fRkPZSvRtNtvxhZhBnfZrlAGzlCj8GE=; b=T/EllNwKUuikFbdlOa97VOLrcyS2w9LCXDn/oea9vLzuLHeJCbp1XKzXIB3WBgu+s4 xV0mYFK56d4AnUaDqfn1pCOxBbrqID5Mp6/wsrmjyQ3r/d9IPog+5Ad0Bu+uxYGY37LA GBqfe2X7GMkcZy5sZ8LkZg+LptBMWTESo3zUdqK10C66dQNQ1ATzYihhi2EMk8PtntUu 6S3Fejj3lsBCL01Ucwq9S6JEOPMXP+CtWLWCx4rIa0EPlwX2Npv1fO+5gGiMt6BEB/a/ BDfWoOKuBQi9m0AvfOHI+YqUQyzQeoLVn+JwTgjX3t/kAKjFpsxVE0QcvwTlq7argz6T xFyw== X-Forwarded-Encrypted: i=1; AJvYcCXPS+Xd0Peo9ShAgqkuwj+mgH7UpecWe/nAVyLLQdza8PJedpEKXwt66hlYPgff99rvnjRf@lists.bufferbloat.net X-Gm-Message-State: AOJu0YzNLe8ouIxymMwP9L/bTiayDnVbYVmqKZcDLxMwK7KUD18iLETk C3TW9b3fgbX6z5UCi7aYDVp2pvCAZ/sxmRYRIHA0arRhGvNOZM2UooD/Z6sH3x3sx14+bnTZ8z3 rxdxPK4SnZbvtCFwog0DM/Ym5/SXBEB0NAceTCPXxvCTCb0xn+Dz3kFlFAvM= X-Gm-Gg: ASbGncuNQhZUqzp/bEnMCHJ5i1fu5LHzqAbwEMUf6Br50iPRH/ALrZSMMviE/bTf3H7 DZy3aS4mnhQUqAXywQMPOMcZR+DyeT3O2Ellejt05QIRidICUTSAIpKLsPmIH469H2z/jyveIG5 ng3uKT6Evo8bpqHw30X+iX5FuUZz8LTyxkKwNjDVcPTTypJQdHCMAqxdH4dDZ/FylIWBNszYZ6C IslPB3QfyMttwT80Vzz8yu/8L6/7nZjNRzBmD1nKSz5f8KMnV477Q== X-Received: by 2002:a17:907:7f0b:b0:aab:dc3e:1c84 with SMTP id a640c23a62f3a-aac2b0a56b6mr5056061866b.17.1736170803485; Mon, 06 Jan 2025 05:40:03 -0800 (PST) X-Google-Smtp-Source: AGHT+IEQ4fy+bYZtT8GzTBXjkHHDP8uRbcLNSuvg0O2pFaTIMwftyd/2R0VX3W1BkcVGNjuwueBrZA== X-Received: by 2002:a17:907:7f0b:b0:aab:dc3e:1c84 with SMTP id a640c23a62f3a-aac2b0a56b6mr5056058366b.17.1736170802870; Mon, 06 Jan 2025 05:40:02 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aac0e892bb7sm2237715766b.43.2025.01.06.05.40.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jan 2025 05:40:02 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 5484A177DEBD; Mon, 06 Jan 2025 14:40:01 +0100 (CET) From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= To: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Jamal Hadi Salim , Cong Wang , Jiri Pirko , Paolo Abeni Cc: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , syzbot+f63600d288bfb7057424@syzkaller.appspotmail.com, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman , cake@lists.bufferbloat.net, netdev@vger.kernel.org Date: Mon, 6 Jan 2025 14:38:36 +0100 Message-ID: <20250106133837.18609-1-toke@redhat.com> X-Mailer: git-send-email 2.47.1 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: JjHlZU0ZD-J0M-7F6WhT2p3fjFbAbjsqsCTRq3_EuVI_1736170804 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Cake] [PATCH net] sched: sch_cake: add bounds checks to host bulk flow fairness counts X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 Jan 2025 13:40:06 -0000 Even though we fixed a logic error in the commit cited below, syzbot still managed to trigger an underflow of the per-host bulk flow counters, leading to an out of bounds memory access. To avoid any such logic errors causing out of bounds memory accesses, this commit factors out all accesses to the per-host bulk flow counters to a series of helpers that perform bounds-checking before any increments and decrements. This also has the benefit of improving readability by moving the conditional checks for the flow mode into these helpers, instead of having them spread out throughout the code (which was the cause of the original logic error). Fixes: 546ea84d07e3 ("sched: sch_cake: fix bulk flow accounting logic for host fairness") Reported-by: syzbot+f63600d288bfb7057424@syzkaller.appspotmail.com Signed-off-by: Toke Høiland-Jørgensen --- net/sched/sch_cake.c | 135 ++++++++++++++++++++++++------------------- 1 file changed, 75 insertions(+), 60 deletions(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 8d8b2db4653c..8f61ecb78139 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -627,6 +627,63 @@ static bool cake_ddst(int flow_mode) return (flow_mode & CAKE_FLOW_DUAL_DST) == CAKE_FLOW_DUAL_DST; } +static void cake_dec_srchost_bulk_flow_count(struct cake_tin_data *q, + struct cake_flow *flow, + int flow_mode) +{ + if (likely(cake_dsrc(flow_mode) && + q->hosts[flow->srchost].srchost_bulk_flow_count)) + q->hosts[flow->srchost].srchost_bulk_flow_count--; +} + +static void cake_inc_srchost_bulk_flow_count(struct cake_tin_data *q, + struct cake_flow *flow, + int flow_mode) +{ + if (likely(cake_dsrc(flow_mode) && + q->hosts[flow->srchost].srchost_bulk_flow_count < CAKE_QUEUES)) + q->hosts[flow->srchost].srchost_bulk_flow_count++; +} + +static void cake_dec_dsthost_bulk_flow_count(struct cake_tin_data *q, + struct cake_flow *flow, + int flow_mode) +{ + if (likely(cake_ddst(flow_mode) && + q->hosts[flow->dsthost].dsthost_bulk_flow_count)) + q->hosts[flow->dsthost].dsthost_bulk_flow_count--; +} + +static void cake_inc_dsthost_bulk_flow_count(struct cake_tin_data *q, + struct cake_flow *flow, + int flow_mode) +{ + if (likely(cake_ddst(flow_mode) && + q->hosts[flow->dsthost].dsthost_bulk_flow_count < CAKE_QUEUES)) + q->hosts[flow->dsthost].dsthost_bulk_flow_count++; +} + +static u16 cake_get_flow_quantum(struct cake_tin_data *q, + struct cake_flow *flow, + int flow_mode) +{ + u16 host_load = 1; + + if (cake_dsrc(flow_mode)) + host_load = max(host_load, + q->hosts[flow->srchost].srchost_bulk_flow_count); + + if (cake_ddst(flow_mode)) + host_load = max(host_load, + q->hosts[flow->dsthost].dsthost_bulk_flow_count); + + /* The get_random_u16() is a way to apply dithering to avoid + * accumulating roundoff errors + */ + return (q->flow_quantum * quantum_div[host_load] + + get_random_u16()) >> 16; +} + static u32 cake_hash(struct cake_tin_data *q, const struct sk_buff *skb, int flow_mode, u16 flow_override, u16 host_override) { @@ -773,10 +830,8 @@ static u32 cake_hash(struct cake_tin_data *q, const struct sk_buff *skb, allocate_dst = cake_ddst(flow_mode); if (q->flows[outer_hash + k].set == CAKE_SET_BULK) { - if (allocate_src) - q->hosts[q->flows[reduced_hash].srchost].srchost_bulk_flow_count--; - if (allocate_dst) - q->hosts[q->flows[reduced_hash].dsthost].dsthost_bulk_flow_count--; + cake_dec_srchost_bulk_flow_count(q, &q->flows[outer_hash + k], flow_mode); + cake_dec_dsthost_bulk_flow_count(q, &q->flows[outer_hash + k], flow_mode); } found: /* reserve queue for future packets in same flow */ @@ -801,9 +856,10 @@ static u32 cake_hash(struct cake_tin_data *q, const struct sk_buff *skb, q->hosts[outer_hash + k].srchost_tag = srchost_hash; found_src: srchost_idx = outer_hash + k; - if (q->flows[reduced_hash].set == CAKE_SET_BULK) - q->hosts[srchost_idx].srchost_bulk_flow_count++; q->flows[reduced_hash].srchost = srchost_idx; + + if (q->flows[reduced_hash].set == CAKE_SET_BULK) + cake_inc_srchost_bulk_flow_count(q, &q->flows[reduced_hash], flow_mode); } if (allocate_dst) { @@ -824,9 +880,10 @@ static u32 cake_hash(struct cake_tin_data *q, const struct sk_buff *skb, q->hosts[outer_hash + k].dsthost_tag = dsthost_hash; found_dst: dsthost_idx = outer_hash + k; - if (q->flows[reduced_hash].set == CAKE_SET_BULK) - q->hosts[dsthost_idx].dsthost_bulk_flow_count++; q->flows[reduced_hash].dsthost = dsthost_idx; + + if (q->flows[reduced_hash].set == CAKE_SET_BULK) + cake_inc_dsthost_bulk_flow_count(q, &q->flows[reduced_hash], flow_mode); } } @@ -1839,10 +1896,6 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, /* flowchain */ if (!flow->set || flow->set == CAKE_SET_DECAYING) { - struct cake_host *srchost = &b->hosts[flow->srchost]; - struct cake_host *dsthost = &b->hosts[flow->dsthost]; - u16 host_load = 1; - if (!flow->set) { list_add_tail(&flow->flowchain, &b->new_flows); } else { @@ -1852,18 +1905,8 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, flow->set = CAKE_SET_SPARSE; b->sparse_flow_count++; - if (cake_dsrc(q->flow_mode)) - host_load = max(host_load, srchost->srchost_bulk_flow_count); - - if (cake_ddst(q->flow_mode)) - host_load = max(host_load, dsthost->dsthost_bulk_flow_count); - - flow->deficit = (b->flow_quantum * - quantum_div[host_load]) >> 16; + flow->deficit = cake_get_flow_quantum(b, flow, q->flow_mode); } else if (flow->set == CAKE_SET_SPARSE_WAIT) { - struct cake_host *srchost = &b->hosts[flow->srchost]; - struct cake_host *dsthost = &b->hosts[flow->dsthost]; - /* this flow was empty, accounted as a sparse flow, but actually * in the bulk rotation. */ @@ -1871,12 +1914,8 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, b->sparse_flow_count--; b->bulk_flow_count++; - if (cake_dsrc(q->flow_mode)) - srchost->srchost_bulk_flow_count++; - - if (cake_ddst(q->flow_mode)) - dsthost->dsthost_bulk_flow_count++; - + cake_inc_srchost_bulk_flow_count(b, flow, q->flow_mode); + cake_inc_dsthost_bulk_flow_count(b, flow, q->flow_mode); } if (q->buffer_used > q->buffer_max_used) @@ -1939,7 +1978,6 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) struct list_head *head; bool first_flow = true; struct sk_buff *skb; - u16 host_load; u64 delay; u32 len; @@ -2042,7 +2080,6 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) /* triple isolation (modified DRR++) */ srchost = &b->hosts[flow->srchost]; dsthost = &b->hosts[flow->dsthost]; - host_load = 1; /* flow isolation (DRR++) */ if (flow->deficit <= 0) { @@ -2055,11 +2092,8 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) b->sparse_flow_count--; b->bulk_flow_count++; - if (cake_dsrc(q->flow_mode)) - srchost->srchost_bulk_flow_count++; - - if (cake_ddst(q->flow_mode)) - dsthost->dsthost_bulk_flow_count++; + cake_inc_srchost_bulk_flow_count(b, flow, q->flow_mode); + cake_inc_dsthost_bulk_flow_count(b, flow, q->flow_mode); flow->set = CAKE_SET_BULK; } else { @@ -2071,19 +2105,7 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) } } - if (cake_dsrc(q->flow_mode)) - host_load = max(host_load, srchost->srchost_bulk_flow_count); - - if (cake_ddst(q->flow_mode)) - host_load = max(host_load, dsthost->dsthost_bulk_flow_count); - - WARN_ON(host_load > CAKE_QUEUES); - - /* The get_random_u16() is a way to apply dithering to avoid - * accumulating roundoff errors - */ - flow->deficit += (b->flow_quantum * quantum_div[host_load] + - get_random_u16()) >> 16; + flow->deficit += cake_get_flow_quantum(b, flow, q->flow_mode); list_move_tail(&flow->flowchain, &b->old_flows); goto retry; @@ -2107,11 +2129,8 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) if (flow->set == CAKE_SET_BULK) { b->bulk_flow_count--; - if (cake_dsrc(q->flow_mode)) - srchost->srchost_bulk_flow_count--; - - if (cake_ddst(q->flow_mode)) - dsthost->dsthost_bulk_flow_count--; + cake_dec_srchost_bulk_flow_count(b, flow, q->flow_mode); + cake_dec_dsthost_bulk_flow_count(b, flow, q->flow_mode); b->decaying_flow_count++; } else if (flow->set == CAKE_SET_SPARSE || @@ -2129,12 +2148,8 @@ static struct sk_buff *cake_dequeue(struct Qdisc *sch) else if (flow->set == CAKE_SET_BULK) { b->bulk_flow_count--; - if (cake_dsrc(q->flow_mode)) - srchost->srchost_bulk_flow_count--; - - if (cake_ddst(q->flow_mode)) - dsthost->dsthost_bulk_flow_count--; - + cake_dec_srchost_bulk_flow_count(b, flow, q->flow_mode); + cake_dec_dsthost_bulk_flow_count(b, flow, q->flow_mode); } else b->decaying_flow_count--; -- 2.47.1