Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752665AbdGJHNk convert rfc822-to-8bit (ORCPT ); Mon, 10 Jul 2017 03:13:40 -0400 Received: from mga02.intel.com ([134.134.136.20]:25878 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751045AbdGJHNi (ORCPT ); Mon, 10 Jul 2017 03:13:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,338,1496127600"; d="scan'208";a="1193461529" From: "Reshetova, Elena" To: "Levin, Alexander (Sasha Levin)" , "Eric Dumazet" CC: "netdev@vger.kernel.org" , "bridge@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "kuznet@ms2.inr.ac.ru" , "jmorris@namei.org" , "kaber@trash.net" , "stephen@networkplumber.org" , "peterz@infradead.org" , "keescook@chromium.org" Subject: RE: [PATCH 00/17] v3 net generic subsystem refcount conversions Thread-Topic: [PATCH 00/17] v3 net generic subsystem refcount conversions Thread-Index: AQHS8YjXsh7pyiPm4ky6PGLI0RjldqJBycAAgAh40QCAAnBdAA== Date: Mon, 10 Jul 2017 07:13:33 +0000 Message-ID: <2236FBA76BA1254E88B949DDB74E612B6FF226C3@IRSMSX102.ger.corp.intel.com> References: <1498817290-3368-1-git-send-email-elena.reshetova@intel.com> <1499074136.1462.0.camel@edumazet-glaptop3.roam.corp.google.com> <20170708185206.jj5mjjasmrd7bjry@sasha-lappy> In-Reply-To: <20170708185206.jj5mjjasmrd7bjry@sasha-lappy> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 10.0.102.7 dlp-reaction: no-action x-originating-ip: [163.33.239.182] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9289 Lines: 191 > On Mon, Jul 03, 2017 at 02:28:56AM -0700, Eric Dumazet wrote: > >On Fri, 2017-06-30 at 13:07 +0300, Elena Reshetova wrote: > >> Changes in v3: > >> Rebased on top of the net-next tree. > >> > >> Changes in v2: > >> No changes in patches apart from rebases, but now by > >> default refcount_t = atomic_t (*) and uses all atomic standard operations > >> unless CONFIG_REFCOUNT_FULL is enabled. This is a compromise for the > >> systems that are critical on performance (such as net) and cannot accept even > >> slight delay on the refcounter operations. > >> > >> This series, for core network subsystem components, replaces atomic_t > reference > >> counters with the new refcount_t type and API (see > include/linux/refcount.h). > >> By doing this we prevent intentional or accidental > >> underflows or overflows that can led to use-after-free vulnerabilities. > >> These patches contain only generic net pieces. Other changes will be sent > separately. > >> > >> The patches are fully independent and can be cherry-picked separately. > >> The big patches, such as conversions for sock structure, need a very detailed > >> look from maintainers: refcount managing is quite complex in them and while > >> it seems that they would benefit from the change, extra checking is needed. > >> The biggest corner issue is the fact that refcount_inc() does not increment > >> from zero. > >> > >> If there are no objections to the patches, please merge them via respective > trees. > >> > >> * The respective change is currently merged into -next as > >> "locking/refcount: Create unchecked atomic_t implementation". > >> > >> Elena Reshetova (17): > >> net: convert inet_peer.refcnt from atomic_t to refcount_t > >> net: convert neighbour.refcnt from atomic_t to refcount_t > >> net: convert neigh_params.refcnt from atomic_t to refcount_t > >> net: convert nf_bridge_info.use from atomic_t to refcount_t > >> net: convert sk_buff.users from atomic_t to refcount_t > >> net: convert sk_buff_fclones.fclone_ref from atomic_t to refcount_t > >> net: convert sock.sk_wmem_alloc from atomic_t to refcount_t > >> net: convert sock.sk_refcnt from atomic_t to refcount_t > >> net: convert ip_mc_list.refcnt from atomic_t to refcount_t > >> net: convert in_device.refcnt from atomic_t to refcount_t > >> net: convert netpoll_info.refcnt from atomic_t to refcount_t > >> net: convert unix_address.refcnt from atomic_t to refcount_t > >> net: convert fib_rule.refcnt from atomic_t to refcount_t > >> net: convert inet_frag_queue.refcnt from atomic_t to refcount_t > >> net: convert net.passive from atomic_t to refcount_t > >> net: convert netlbl_lsm_cache.refcount from atomic_t to refcount_t > >> net: convert packet_fanout.sk_ref from atomic_t to refcount_t > > > > > >Can you take a look at this please ? > > > >[ 64.601749] ------------[ cut here ]------------ > >[ 64.601757] WARNING: CPU: 0 PID: 6476 at lib/refcount.c:184 > refcount_sub_and_test+0x75/0xa0 > >[ 64.601758] Modules linked in: w1_therm wire cdc_acm ehci_pci ehci_hcd > mlx4_en ib_uverbs mlx4_ib ib_core mlx4_core > >[ 64.601769] CPU: 0 PID: 6476 Comm: ip Tainted: G W 4.12.0-smp-DEV > #274 > >[ 64.601770] Hardware name: Intel RML,PCH/Iota_QC_19, BIOS 2.40.0 > 06/22/2016 > >[ 64.601771] task: ffff8837bf482040 task.stack: ffff8837bdc08000 > >[ 64.601773] RIP: 0010:refcount_sub_and_test+0x75/0xa0 > >[ 64.601774] RSP: 0018:ffff8837bdc0f5c0 EFLAGS: 00010286 > >[ 64.601776] RAX: 0000000000000026 RBX: 0000000000000001 RCX: > 0000000000000000 > >[ 64.601777] RDX: 0000000000000026 RSI: 0000000000000096 RDI: > ffffed06f7b81eae > >[ 64.601778] RBP: ffff8837bdc0f5d0 R08: 0000000000000004 R09: > fffffbfff4a54c25 > >[ 64.601779] R10: 00000000cbc500e5 R11: ffffffffa52a6128 R12: ffff881febcf6f24 > >[ 64.601779] R13: ffff881fbf4eaf00 R14: ffff881febcf6f80 R15: ffff8837d7a4ed00 > >[ 64.601781] FS: 00007ff5a2f6b700(0000) GS:ffff881fff800000(0000) > knlGS:0000000000000000 > >[ 64.601782] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >[ 64.601783] CR2: 00007ffcdc70d000 CR3: 0000001f9c91e000 CR4: > 00000000001406f0 > >[ 64.601783] Call Trace: > >[ 64.601786] refcount_dec_and_test+0x11/0x20 > >[ 64.601790] fib_nl_delrule+0xc39/0x1630 > [snip] > > I'm seeing a similar one coming from sctp: > > refcount_t: underflow; use-after-free. > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 15570 at lib/refcount.c:186 > refcount_sub_and_test.cold.13+0x18/0x21 lib/refcount.c:186 > Kernel panic - not syncing: panic_on_warn set ... > > CPU: 3 PID: 15570 Comm: syz-executor0 Not tainted 4.12.0-next-20170706+ #186 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 > 04/01/2014 > Call Trace: > __dump_stack lib/dump_stack.c:16 [inline] > dump_stack+0x11d/0x1ef lib/dump_stack.c:52 > panic+0x1bc/0x3ad kernel/panic.c:180 > __warn.cold.6+0x2f/0x2f kernel/panic.c:541 > report_bug+0x20d/0x2d0 lib/bug.c:183 > fixup_bug+0x3f/0x90 arch/x86/kernel/traps.c:190 > do_trap_no_signal arch/x86/kernel/traps.c:224 [inline] > do_trap+0x132/0x390 arch/x86/kernel/traps.c:273 > do_error_trap+0x133/0x380 arch/x86/kernel/traps.c:310 > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323 > invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:845 > RIP: 0010:refcount_sub_and_test.cold.13+0x18/0x21 lib/refcount.c:186 > RSP: 0018:ffff880062f7e270 EFLAGS: 00010282 > RAX: 0000000000000026 RBX: ffff88006086a8cc RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 1ffff1000c5efc0a RDI: ffffffffac15c400 > RBP: ffff880062f7e2f8 R08: 0000000000000006 R09: 0000000000000000 > R10: ffff880069914040 R11: 0000000000000000 R12: 00000000ffffff01 > R13: 0000000000000100 R14: 1ffff1000c5efc4e R15: 0000000000000001 > sctp_wfree+0x183/0x620 net/sctp/socket.c:7745 > skb_release_head_state+0x124/0x250 net/core/skbuff.c:652 > skb_release_all+0x15/0x60 net/core/skbuff.c:665 > __kfree_skb net/core/skbuff.c:681 [inline] > consume_skb+0x16c/0x500 net/core/skbuff.c:748 > sctp_chunk_destroy net/sctp/sm_make_chunk.c:1441 [inline] > sctp_chunk_put+0x206/0x430 net/sctp/sm_make_chunk.c:1468 > sctp_chunk_free+0x53/0x60 net/sctp/sm_make_chunk.c:1455 > __sctp_outq_teardown+0x274/0x15b0 net/sctp/outqueue.c:228 > sctp_outq_free+0x15/0x20 net/sctp/outqueue.c:284 > sctp_association_free+0x2d4/0x934 net/sctp/associola.c:358 > sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:917 [inline] > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1333 [inline] > sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline] > sctp_do_sm+0x4024/0x6d60 net/sctp/sm_sideeffect.c:1170 > sctp_primitive_ABORT+0xa0/0xd0 net/sctp/primitive.c:119 > sctp_close+0x293/0x9b0 net/sctp/socket.c:1529 > inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425 > inet6_release+0x50/0x70 net/ipv6/af_inet6.c:432 > sock_release+0x8d/0x1b0 net/socket.c:597 > sock_close+0x16/0x20 net/socket.c:1112 > __fput+0x327/0x920 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:246 > llcp: llcp_sock_recvmsg: Recv datagram failed state 5 -11 0 > task_work_run+0x192/0x270 kernel/task_work.c:116 > exit_task_work include/linux/task_work.h:21 [inline] > do_exit+0xa42/0x1ba0 kernel/exit.c:864 > do_group_exit+0x151/0x410 kernel/exit.c:966 > get_signal+0x84e/0x18a0 kernel/signal.c:2330 > do_signal+0x9c/0x2210 arch/x86/kernel/signal.c:808 > exit_to_usermode_loop+0x187/0x220 arch/x86/entry/common.c:157 > prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] > syscall_return_slowpath arch/x86/entry/common.c:263 [inline] > do_syscall_64+0x50b/0x740 arch/x86/entry/common.c:289 > llcp: llcp_sock_recvmsg: Recv datagram failed state 5 -11 0 > entry_SYSCALL64_slow_path+0x25/0x25 > RIP: 0033:0x452309 > RSP: 002b:00007f6aed443cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 0000000000718218 RCX: 0000000000452309 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000718218 > RBP: 00000000007181f8 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffb90a5aae > R13: 00007fffb90a5aaf R14: 00007f6aed4449c0 R15: 00007f6aed444700 > Dumping ftrace buffer: > (ftrace buffer empty) > Kernel Offset: 0x24000000 from 0xffffffff81000000 (relocation range: > 0xffffffff80000000-0xffffffffbfffffff) > Rebooting in 86400 seconds.. > Thank you for reporting this! However, I might need some help checking what is going on there. Your kernel is enabled to panic on warn, which is great since it gives us understanding that this is a different issue than previous one (otherwise we would see a panic earlier when failing to increment from zero somewhere). The code that causes the warning here is this: @@ -7684,7 +7684,7 @@ static void sctp_wfree(struct sk_buff *skb) sizeof(struct sk_buff) + sizeof(struct sctp_chunk); - atomic_sub(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc); + WARN_ON(refcount_sub_and_test(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc)); As you can see previously it would just do a atomic_sub() and not care of end result, but now it issues a warning if result underflows. Is it possible that it just uncovered the existing bug or was it supposed to underflow in certain conditions? Best Regards, Elena. > -- > > Thanks, > Sasha