From patchwork Mon May 13 16:59:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 1098989 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="tsPPx9G9"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 452n955WkYz9s00 for ; Tue, 14 May 2019 02:59:21 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730018AbfEMQ7U (ORCPT ); Mon, 13 May 2019 12:59:20 -0400 Received: from mail-pg1-f202.google.com ([209.85.215.202]:34317 "EHLO mail-pg1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729650AbfEMQ7U (ORCPT ); Mon, 13 May 2019 12:59:20 -0400 Received: by mail-pg1-f202.google.com with SMTP id z7so9584768pgc.1 for ; Mon, 13 May 2019 09:59:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=3cOYEKKvk6z+zsgzYfoEXAvcfcEGnzEvXzE0Cid7gi0=; b=tsPPx9G9DnakEWknuekFc2N5HipsZv24ezd4Ev1+u2ngFhmtDGkvDyM1OuK0wFfgyO mC8dEpurynoMgE2/AGJwCWt6FLErTAuXZOzb9rHQWmTuwPMFe5Iy8f19J8uP07jtHQJK pm1algwdM/iksIT0HH3rkhLAbq+BrAx5Ei/S8KNgT93ce2q0w8JVcg42cRmXl2Jd1IOw 2zYc9/6QYOXg++APE3nf8zzGJj4s8jgsSWaooQfpD/e79w3ZDPGjVFFbHhVGAJpXFanT QHPq70VRMSIeB6nsJ14DVIr9EcSLUTGiykUkRo+eHZtJX9dyPJyB5FzJQkk2lz9fxq+0 kdQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=3cOYEKKvk6z+zsgzYfoEXAvcfcEGnzEvXzE0Cid7gi0=; b=soB0p8+UUnN1y+em2kluUBpaU0xtN7KE3CgpuHF7nv3vhVKb7Fpo0CNycXANOayLDJ 1RTtbTSrp3PDJTHaj4KNya8lmQAt5aooKs7Wdli6JCQMNbhmBxa30QTbjCx6PMwZD6+M e0gKqADoKe7CLtcOzRIuWfwQFDwt2WAJHkGd/o/pofnBXdJ5Zpb432J7Y92ZU3RdeDYY R6GIAOfe3tqcaKJj4sX8GqqRWHQzz273ViK9SdLHvi86faVLQcfUHUoaUClcfH50q/ux GP9rChMmD7RBo7kbhax0UawCuAP29Dzh2rJbCJb92eX0yHW7xVO5HGYuprrDsOHy8a6D 45/Q== X-Gm-Message-State: APjAAAW5YAmr03JAbyd+TR3eJJGpn9c9mlg8ShR4ue4Rdm9pIsEJQV23 onem9ypTnwZ9KBRG2gFKRX9cENbQfLgpPQ== X-Google-Smtp-Source: APXvYqznBPczJl6YOrY96mnx6E3eiJ064D+vOCus2SHa4iLhb2/DXSyg83tcd34hRfEtAJL9+tvfMVjUPRu97Q== X-Received: by 2002:a63:7982:: with SMTP id u124mr32165268pgc.352.1557766759318; Mon, 13 May 2019 09:59:19 -0700 (PDT) Date: Mon, 13 May 2019 09:59:16 -0700 Message-Id: <20190513165916.259013-1-edumazet@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH net] bpf: devmap: fix use-after-free Read in __dev_map_entry_free From: Eric Dumazet To: Alexei Starovoitov , Daniel Borkmann Cc: "David S . Miller" , netdev , Eric Dumazet , Eric Dumazet , bpf , syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com, "=?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?=" , Jesper Dangaard Brouer Sender: bpf-owner@vger.kernel.org Precedence: bulk List-Id: netdev.vger.kernel.org synchronize_rcu() is fine when the rcu callbacks only need to free memory (kfree_rcu() or direct kfree() call rcu call backs) __dev_map_entry_free() is a bit more complex, so we need to make sure that call queued __dev_map_entry_free() callbacks have completed. sysbot report: BUG: KASAN: use-after-free in dev_map_flush_old kernel/bpf/devmap.c:365 [inline] BUG: KASAN: use-after-free in __dev_map_entry_free+0x2a8/0x300 kernel/bpf/devmap.c:379 Read of size 8 at addr ffff8801b8da38c8 by task ksoftirqd/1/18 CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.17.0+ #39 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 dev_map_flush_old kernel/bpf/devmap.c:365 [inline] __dev_map_entry_free+0x2a8/0x300 kernel/bpf/devmap.c:379 __rcu_reclaim kernel/rcu/rcu.h:178 [inline] rcu_do_batch kernel/rcu/tree.c:2558 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2818 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2785 [inline] rcu_process_callbacks+0xe9d/0x1760 kernel/rcu/tree.c:2802 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284 run_ksoftirqd+0x86/0x100 kernel/softirq.c:645 smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Allocated by task 6675: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:706 [inline] dev_map_alloc+0x208/0x7f0 kernel/bpf/devmap.c:102 find_and_alloc_map kernel/bpf/syscall.c:129 [inline] map_create+0x393/0x1010 kernel/bpf/syscall.c:453 __do_sys_bpf kernel/bpf/syscall.c:2351 [inline] __se_sys_bpf kernel/bpf/syscall.c:2328 [inline] __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2328 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 26: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 dev_map_free+0x4fa/0x670 kernel/bpf/devmap.c:191 bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 The buggy address belongs to the object at ffff8801b8da37c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 264 bytes inside of 512-byte region [ffff8801b8da37c0, ffff8801b8da39c0) The buggy address belongs to the page: page:ffffea0006e368c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0xffff8801b8da3540 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0007217b88 ffffea0006e30cc8 ffff8801da800940 raw: ffff8801b8da3540 ffff8801b8da3040 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801b8da3780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8801b8da3800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801b8da3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801b8da3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b8da3980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references") Signed-off-by: Eric Dumazet Reported-by: syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com Acked-by: Toke Høiland-Jørgensen Acked-by: Jesper Dangaard Brouer --- kernel/bpf/devmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 191b79948424f4b21b7aa120abc03801264bf0a6..1e525d70f83354e451b738ffb8e42d83b5fa932f 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -164,6 +164,9 @@ static void dev_map_free(struct bpf_map *map) bpf_clear_redirect_map(map); synchronize_rcu(); + /* Make sure prior __dev_map_entry_free() have completed. */ + rcu_barrier(); + /* To ensure all pending flush operations have completed wait for flush * bitmap to indicate all flush_needed bits to be zero on _all_ cpus. * Because the above synchronize_rcu() ensures the map is disconnected