From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C6DAC433FF for ; Sat, 10 Aug 2019 20:47:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5077F208C3 for ; Sat, 10 Aug 2019 20:47:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727424AbfHJUrb (ORCPT ); Sat, 10 Aug 2019 16:47:31 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55034 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726836AbfHJUoE (ORCPT ); Sat, 10 Aug 2019 16:44:04 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hwYDY-00058O-Eh; Sat, 10 Aug 2019 21:44:00 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hwYDN-0003hy-EP; Sat, 10 Aug 2019 21:43:49 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Eric W. Biederman" , "Eric Dumazet" , "David S. Miller" , "syzbot" Date: Sat, 10 Aug 2019 21:40:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 116/157] ipv6/flowlabel: wait rcu grace period before put_pid() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 6c0afef5fb0c27758f4d52b2210c61b6bd8b4470 upstream. syzbot was able to catch a use-after-free read in pid_nr_ns() [1] ip6fl_seq_show() seems to use RCU protection, dereferencing fl->owner.pid but fl_free() releases fl->owner.pid before rcu grace period is started. [1] BUG: KASAN: use-after-free in pid_nr_ns+0x128/0x140 kernel/pid.c:407 Read of size 4 at addr ffff888094012a04 by task syz-executor.0/18087 CPU: 0 PID: 18087 Comm: syz-executor.0 Not tainted 5.1.0-rc6+ #89 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+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131 pid_nr_ns+0x128/0x140 kernel/pid.c:407 ip6fl_seq_show+0x2f8/0x4f0 net/ipv6/ip6_flowlabel.c:794 seq_read+0xad3/0x1130 fs/seq_file.c:268 proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:922 vfs_readv+0xf0/0x160 fs/read_write.c:984 kernel_readv fs/splice.c:358 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:413 do_splice_to+0x12a/0x190 fs/splice.c:876 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 do_sendfile+0x597/0xd00 fs/read_write.c:1443 __do_sys_sendfile64 fs/read_write.c:1498 [inline] __se_sys_sendfile64 fs/read_write.c:1490 [inline] __x64_sys_sendfile64+0x15a/0x220 fs/read_write.c:1490 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458da9 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f300d24bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458da9 RDX: 00000000200000c0 RSI: 0000000000000008 RDI: 0000000000000007 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000005a R11: 0000000000000246 R12: 00007f300d24c6d4 R13: 00000000004c5fa3 R14: 00000000004da748 R15: 00000000ffffffff Allocated by task 17543: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_kmalloc mm/kasan/common.c:497 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:505 slab_post_alloc_hook mm/slab.h:437 [inline] slab_alloc mm/slab.c:3393 [inline] kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3555 alloc_pid+0x55/0x8f0 kernel/pid.c:168 copy_process.part.0+0x3b08/0x7980 kernel/fork.c:1932 copy_process kernel/fork.c:1709 [inline] _do_fork+0x257/0xfd0 kernel/fork.c:2226 __do_sys_clone kernel/fork.c:2333 [inline] __se_sys_clone kernel/fork.c:2327 [inline] __x64_sys_clone+0xbf/0x150 kernel/fork.c:2327 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7789: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459 kasan_slab_free+0xe/0x10 mm/kasan/common.c:467 __cache_free mm/slab.c:3499 [inline] kmem_cache_free+0x86/0x260 mm/slab.c:3765 put_pid.part.0+0x111/0x150 kernel/pid.c:111 put_pid+0x20/0x30 kernel/pid.c:105 fl_free+0xbe/0xe0 net/ipv6/ip6_flowlabel.c:102 ip6_fl_gc+0x295/0x3e0 net/ipv6/ip6_flowlabel.c:152 call_timer_fn+0x190/0x720 kernel/time/timer.c:1325 expire_timers kernel/time/timer.c:1362 [inline] __run_timers kernel/time/timer.c:1681 [inline] __run_timers kernel/time/timer.c:1649 [inline] run_timer_softirq+0x652/0x1700 kernel/time/timer.c:1694 __do_softirq+0x266/0x95a kernel/softirq.c:293 The buggy address belongs to the object at ffff888094012a00 which belongs to the cache pid_2 of size 88 The buggy address is located 4 bytes inside of 88-byte region [ffff888094012a00, ffff888094012a58) The buggy address belongs to the page: page:ffffea0002500480 count:1 mapcount:0 mapping:ffff88809a483080 index:0xffff888094012980 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea00018a3508 ffffea0002524a88 ffff88809a483080 raw: ffff888094012980 ffff888094012000 000000010000001b 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888094012900: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc ffff888094012980: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc >ffff888094012a00: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc ^ ffff888094012a80: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc ffff888094012b00: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc Fixes: 4f82f45730c6 ("net ip6 flowlabel: Make owner a union of struct pid * and kuid_t") Signed-off-by: Eric Dumazet Cc: Eric W. Biederman Reported-by: syzbot Signed-off-by: David S. Miller [bwh: Backported to 3.16: Move the release_net() call too, not that it does anything.] Signed-off-by: Ben Hutchings --- --- a/net/ipv6/ip6_flowlabel.c +++ b/net/ipv6/ip6_flowlabel.c @@ -94,16 +94,22 @@ static struct ip6_flowlabel *fl_lookup(s return fl; } +static void fl_free_rcu(struct rcu_head *head) +{ + struct ip6_flowlabel *fl = container_of(head, struct ip6_flowlabel, rcu); + + if (fl->share == IPV6_FL_S_PROCESS) + put_pid(fl->owner.pid); + release_net(fl->fl_net); + kfree(fl->opt); + kfree(fl); +} + static void fl_free(struct ip6_flowlabel *fl) { - if (fl) { - if (fl->share == IPV6_FL_S_PROCESS) - put_pid(fl->owner.pid); - release_net(fl->fl_net); - kfree(fl->opt); - kfree_rcu(fl, rcu); - } + if (fl) + call_rcu(&fl->rcu, fl_free_rcu); } static void fl_release(struct ip6_flowlabel *fl)