From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f45.google.com (mail-ot1-f45.google.com [209.85.210.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6C48D55C3B for ; Tue, 14 May 2024 12:41:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715690478; cv=none; b=UVm6gTwCKd01hFewDXVDvhRDq9YTUA9rmO2ELbXQaNJ7BynRlOLNEdBbr+COgbIROnmliFC6Gwwt9KZnvKrX8XtwAOCnBZLBnZcysPL8tAB8fTyjFVuzdOB+R9zZBqQCBdh4CHZr8n9KbDpVSTaExWOI5VYTk5TEbvX0QlmqsQY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715690478; c=relaxed/simple; bh=uowLP++liw21uF2zuo/eKfAR23hS3OQREjM5sUi3QDU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LhvXu3fqSFaDrVUF+M57iZ9EZ8X2alsDT7AcPJpxtAaQbHA7rP4LubxMxjbF4wNPULoMPwYtMyhYUWeBk9XUzKmL2CposViUohuLVV4+3yojJp2L0YBy1twExlARfghX8RzCN1SdGzIF+vhYHAjddP/5bXDodZwuF3T4+QYaqiw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=A9F6fUsw; arc=none smtp.client-ip=209.85.210.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="A9F6fUsw" Received: by mail-ot1-f45.google.com with SMTP id 46e09a7af769-6f0e2612303so3070482a34.2 for ; Tue, 14 May 2024 05:41:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1715690476; x=1716295276; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ypCihyheNflK1mbusL6H8ZCmjUFQCxzxR9a9qXg+FaI=; b=A9F6fUswW9BmI3pemEPXkaGpS/ESkz6H9dnuyaYi8Y1J+kJ38lkojOszdxcA7B2OHj g9pDef3CvxOZeKy+6cueiAkvJo439uDjt4teRMQLO93vwdzhaS+xfv6ZH4J9aX6Fd3kg uqdmO2h7JRZayjdifg/8daBkWfw67R/eSMA+caq+mjxxeHpxgJqW/cV5hrKy3Wg56GEz TvQecTDaT1nWk0WKTJLi1cM/XcirVg1+lz3zayq50J1/O5G4Rx7uMx2JeHeYL1HtOYw+ 7m8W5eEvdNuB83p4blYaa8DatUFVnZVQohyoZO7Gq8mc144yJnmGstNV/JVFggIk3vcQ o7qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1715690476; x=1716295276; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ypCihyheNflK1mbusL6H8ZCmjUFQCxzxR9a9qXg+FaI=; b=l9jarDtlXz6ar1umnRNoO0HnQS3duz3420WBfxoJPxQ3l2Qs0qXSZPE6G7yX/77g0H cXVfClXBCmgMhyzQpxPR5ROCQXmq8b+xM5oSZy+TNVs01C9OhAPCTTUwcBAZjSZ4o/fy dpA01KoATypkBtCkkIM/nXpEfSR775dSKymq2/cafbq5uCyb2f4SuDs3GbkYUhwMS6f/ 3iRK86pr/RnLh6m5QRdi60Nj4/W1IKg06FJPbha0a//o7K6re6GD6wAPpzQ/JBVYGX5A aEFDhFPBYHDJ5UpQsTXIuN0AQQL8yEsQBWKAlBpf7W5YERm7aaQBRRt5TAEi8W0hYHmr DyQg== X-Gm-Message-State: AOJu0YweKwqXxQSz+VBbWNFSRSlIpwVUgNA+9F9/zJNhUBnAuAD8NyKW v/dXIeDo2mbV2xnAqUp1SMlfsBHo8AbI+19uN8bK4oAja+Kvk/fRogp4AA== X-Google-Smtp-Source: AGHT+IEMOPqd2U633nnLPc6hpzPS6QpR3RpJC6j1x6BGQzLltIrGchlKHIx7NWy/C1hbfTaZ20diSQ== X-Received: by 2002:a9d:6d95:0:b0:6f0:7986:7821 with SMTP id 46e09a7af769-6f0e929fc3cmr14228198a34.28.1715690476175; Tue, 14 May 2024 05:41:16 -0700 (PDT) Received: from fedora.. ([2607:b400:30:a100:6442:5b0e:54ab:110b]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-43e12f41a0asm31923981cf.48.2024.05.14.05.41.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 May 2024 05:41:15 -0700 (PDT) From: Siddharth Chintamaneni To: bpf@vger.kernel.org Cc: alexei.starovoitov@gmail.com, daniel@iogearbox.net, olsajiri@gmail.com, andrii@kernel.org, yonghong.song@linux.dev, rjsu26@vt.edu, sairoop@vt.edu, miloc@vt.edu, memxor@gmail.com, Siddharth Chintamaneni , syzbot+8bdfc2c53fb2b63e1871@syzkaller.appspotmail.com Subject: [PATCH v3 bpf-next 1/2] bpf: Patch to Fix deadlocks in queue and stack maps Date: Tue, 14 May 2024 08:40:52 -0400 Message-ID: <20240514124052.1240266-2-sidchintamaneni@gmail.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240514124052.1240266-1-sidchintamaneni@gmail.com> References: <20240514124052.1240266-1-sidchintamaneni@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This patch is a revised version which addresses a possible deadlock issue in queue and stack map types. Deadlock could happen when a nested BPF program acquires the same lock as the parent BPF program to perform a write operation on the same map as the first one. This bug is also reported by syzbot. Link: https://lore.kernel.org/lkml/0000000000004c3fc90615f37756@google.com/ Reported-by: syzbot+8bdfc2c53fb2b63e1871@syzkaller.appspotmail.com Fixes: f1a2e44a3aec ("bpf: add queue and stack maps") Signed-off-by: Siddharth Chintamaneni --- kernel/bpf/queue_stack_maps.c | 76 +++++++++++++++++++++++++++++++++-- 1 file changed, 73 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c index d869f51ea93a..b5ed76c9ddd7 100644 --- a/kernel/bpf/queue_stack_maps.c +++ b/kernel/bpf/queue_stack_maps.c @@ -13,11 +13,13 @@ #define QUEUE_STACK_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK) + struct bpf_queue_stack { struct bpf_map map; raw_spinlock_t lock; u32 head, tail; u32 size; /* max_entries + 1 */ + int __percpu *map_locked; char elements[] __aligned(8); }; @@ -78,6 +80,15 @@ static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) qs->size = size; + qs->map_locked = bpf_map_alloc_percpu(&qs->map, + sizeof(int), + sizeof(int), + GFP_USER | __GFP_NOWARN); + if (!qs->map_locked) { + bpf_map_area_free(qs); + return ERR_PTR(-ENOMEM); + } + raw_spin_lock_init(&qs->lock); return &qs->map; @@ -88,19 +99,57 @@ static void queue_stack_map_free(struct bpf_map *map) { struct bpf_queue_stack *qs = bpf_queue_stack(map); + free_percpu(qs->map_locked); bpf_map_area_free(qs); } +static inline int map_lock_inc(struct bpf_queue_stack *qs) +{ + unsigned long flags; + + preempt_disable(); + local_irq_save(flags); + if (unlikely(__this_cpu_inc_return(*(qs->map_locked)) != 1)) { + __this_cpu_dec(*(qs->map_locked)); + local_irq_restore(flags); + preempt_enable(); + return -EBUSY; + } + + local_irq_restore(flags); + preempt_enable(); + + return 0; +} + +static inline void map_unlock_dec(struct bpf_queue_stack *qs) +{ + unsigned long flags; + + preempt_disable(); + local_irq_save(flags); + __this_cpu_dec(*(qs->map_locked)); + local_irq_restore(flags); + preempt_enable(); +} + static long __queue_map_get(struct bpf_map *map, void *value, bool delete) { struct bpf_queue_stack *qs = bpf_queue_stack(map); unsigned long flags; int err = 0; void *ptr; + int ret; + + ret = map_lock_inc(qs); + if (ret) + return ret; if (in_nmi()) { - if (!raw_spin_trylock_irqsave(&qs->lock, flags)) + if (!raw_spin_trylock_irqsave(&qs->lock, flags)) { + map_unlock_dec(qs); return -EBUSY; + } } else { raw_spin_lock_irqsave(&qs->lock, flags); } @@ -121,6 +170,8 @@ static long __queue_map_get(struct bpf_map *map, void *value, bool delete) out: raw_spin_unlock_irqrestore(&qs->lock, flags); + map_unlock_dec(qs); + return err; } @@ -132,10 +183,17 @@ static long __stack_map_get(struct bpf_map *map, void *value, bool delete) int err = 0; void *ptr; u32 index; + int ret; + + ret = map_lock_inc(qs); + if (ret) + return ret; if (in_nmi()) { - if (!raw_spin_trylock_irqsave(&qs->lock, flags)) + if (!raw_spin_trylock_irqsave(&qs->lock, flags)) { + map_unlock_dec(qs); return -EBUSY; + } } else { raw_spin_lock_irqsave(&qs->lock, flags); } @@ -158,6 +216,8 @@ static long __stack_map_get(struct bpf_map *map, void *value, bool delete) out: raw_spin_unlock_irqrestore(&qs->lock, flags); + map_unlock_dec(qs); + return err; } @@ -193,6 +253,7 @@ static long queue_stack_map_push_elem(struct bpf_map *map, void *value, unsigned long irq_flags; int err = 0; void *dst; + int ret; /* BPF_EXIST is used to force making room for a new element in case the * map is full @@ -203,9 +264,16 @@ static long queue_stack_map_push_elem(struct bpf_map *map, void *value, if (flags & BPF_NOEXIST || flags > BPF_EXIST) return -EINVAL; + + ret = map_lock_inc(qs); + if (ret) + return ret; + if (in_nmi()) { - if (!raw_spin_trylock_irqsave(&qs->lock, irq_flags)) + if (!raw_spin_trylock_irqsave(&qs->lock, irq_flags)) { + map_unlock_dec(qs); return -EBUSY; + } } else { raw_spin_lock_irqsave(&qs->lock, irq_flags); } @@ -228,6 +296,8 @@ static long queue_stack_map_push_elem(struct bpf_map *map, void *value, out: raw_spin_unlock_irqrestore(&qs->lock, irq_flags); + map_unlock_dec(qs); + return err; } -- 2.44.0