1. 24 May, 2017 5 commits
    • Alexander Potapenko's avatar
      net: rtnetlink: bail out from rtnl_fdb_dump() on parse error · 0ff50e83
      Alexander Potapenko authored
      rtnl_fdb_dump() failed to check the result of nlmsg_parse(), which led
      to contents of |ifm| being uninitialized because nlh->nlmsglen was too
      small to accommodate |ifm|. The uninitialized data may affect some
      branches and result in unwanted effects, although kernel data doesn't
      seem to leak to the userspace directly.
      
      The bug has been detected with KMSAN and syzkaller.
      
      For the record, here is the KMSAN report:
      
      ==================================================================
      BUG: KMSAN: use of unitialized memory in rtnl_fdb_dump+0x5dc/0x1000
      CPU: 0 PID: 1039 Comm: probe Not tainted 4.11.0-rc5+ #2727
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
      Call Trace:
       __dump_stack lib/dump_stack.c:16
       dump_stack+0x143/0x1b0 lib/dump_stack.c:52
       kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007
       __kmsan_warning_32+0x66/0xb0 mm/kmsan/kmsan_instr.c:491
       rtnl_fdb_dump+0x5dc/0x1000 net/core/rtnetlink.c:3230
       netlink_dump+0x84f/0x1190 net/netlink/af_netlink.c:2168
       __netlink_dump_start+0xc97/0xe50 net/netlink/af_netlink.c:2258
       netlink_dump_start ./include/linux/netlink.h:165
       rtnetlink_rcv_msg+0xae9/0xb40 net/core/rtnetlink.c:4094
       netlink_rcv_skb+0x339/0x5a0 net/netlink/af_netlink.c:2339
       rtnetlink_rcv+0x83/0xa0 net/core/rtnetlink.c:4110
       netlink_unicast_kernel net/netlink/af_netlink.c:1272
       netlink_unicast+0x13b7/0x1480 net/netlink/af_netlink.c:1298
       netlink_sendmsg+0x10b8/0x10f0 net/netlink/af_netlink.c:1844
       sock_sendmsg_nosec net/socket.c:633
       sock_sendmsg net/socket.c:643
       ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997
       __sys_sendmsg net/socket.c:2031
       SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042
       SyS_sendmsg+0x87/0xb0 net/socket.c:2038
       do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285
       entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:246
      RIP: 0033:0x401300
      RSP: 002b:00007ffc3b0e6d58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
      RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000401300
      RDX: 0000000000000000 RSI: 00007ffc3b0e6d80 RDI: 0000000000000003
      RBP: 00007ffc3b0e6e00 R08: 000000000000000b R09: 0000000000000004
      R10: 000000000000000d R11: 0000000000000246 R12: 0000000000000000
      R13: 00000000004065a0 R14: 0000000000406630 R15: 0000000000000000
      origin: 000000008fe00056
       save_stack_trace+0x59/0x60 arch/x86/kernel/stacktrace.c:59
       kmsan_save_stack_with_flags mm/kmsan/kmsan.c:352
       kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:247
       kmsan_poison_shadow+0x6d/0xc0 mm/kmsan/kmsan.c:260
       slab_alloc_node mm/slub.c:2743
       __kmalloc_node_track_caller+0x1f4/0x390 mm/slub.c:4349
       __kmalloc_reserve net/core/skbuff.c:138
       __alloc_skb+0x2cd/0x740 net/core/skbuff.c:231
       alloc_skb ./include/linux/skbuff.h:933
       netlink_alloc_large_skb net/netlink/af_netlink.c:1144
       netlink_sendmsg+0x934/0x10f0 net/netlink/af_netlink.c:1819
       sock_sendmsg_nosec net/socket.c:633
       sock_sendmsg net/socket.c:643
       ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997
       __sys_sendmsg net/socket.c:2031
       SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042
       SyS_sendmsg+0x87/0xb0 net/socket.c:2038
       do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285
       return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:246
      ==================================================================
      
      and the reproducer:
      
      ==================================================================
        #include <sys/socket.h>
        #include <net/if_arp.h>
        #include <linux/netlink.h>
        #include <stdint.h>
      
        int main()
        {
          int sock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK, 0);
          struct msghdr msg;
          memset(&msg, 0, sizeof(msg));
          char nlmsg_buf[32];
          memset(nlmsg_buf, 0, sizeof(nlmsg_buf));
          struct nlmsghdr *nlmsg = nlmsg_buf;
          nlmsg->nlmsg_len = 0x11;
          nlmsg->nlmsg_type = 0x1e; // RTM_NEWROUTE = RTM_BASE + 0x0e
          // type = 0x0e = 1110b
          // kind = 2
          nlmsg->nlmsg_flags = 0x101; // NLM_F_ROOT | NLM_F_REQUEST
          nlmsg->nlmsg_seq = 0;
          nlmsg->nlmsg_pid = 0;
          nlmsg_buf[16] = (char)7;
          struct iovec iov;
          iov.iov_base = nlmsg_buf;
          iov.iov_len = 17;
          msg.msg_iov = &iov;
          msg.msg_iovlen = 1;
          sendmsg(sock, &msg, 0);
          return 0;
        }
      ==================================================================
      Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      0ff50e83
    • Quentin Schulz's avatar
      net: fec: add post PHY reset delay DT property · 159a0760
      Quentin Schulz authored
      Some PHY require to wait for a bit after the reset GPIO has been
      toggled. This adds support for the DT property `phy-reset-post-delay`
      which gives the delay in milliseconds to wait after reset.
      
      If the DT property is not given, no delay is observed. Post reset delay
      greater than 1000ms are invalid.
      Signed-off-by: default avatarQuentin Schulz <quentin.schulz@free-electrons.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Acked-by: default avatarFugang Duan <fugang.duan@nxp.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      159a0760
    • David S. Miller's avatar
      Merge branch 'sctp-dupcookie-fixes' · 11d3c949
      David S. Miller authored
      Xin Long says:
      
      ====================
      sctp: a bunch of fixes for processing dupcookie
      
      After introducing transport hashtable and per stream info into sctp,
      some regressions were caused when processing dupcookie, this patchset
      is to fix them.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      11d3c949
    • Xin Long's avatar
      sctp: set new_asoc temp when processing dupcookie · 7e062977
      Xin Long authored
      After sctp changed to use transport hashtable, a transport would be
      added into global hashtable when adding the peer to an asoc, then
      the asoc can be got by searching the transport in the hashtbale.
      
      The problem is when processing dupcookie in sctp_sf_do_5_2_4_dupcook,
      a new asoc would be created. A peer with the same addr and port as
      the one in the old asoc might be added into the new asoc, but fail
      to be added into the hashtable, as they also belong to the same sk.
      
      It causes that sctp's dupcookie processing can not really work.
      
      Since the new asoc will be freed after copying it's information to
      the old asoc, it's more like a temp asoc. So this patch is to fix
      it by setting it as a temp asoc to avoid adding it's any transport
      into the hashtable and also avoid allocing assoc_id.
      
      An extra thing it has to do is to also alloc stream info for any
      temp asoc, as sctp dupcookie process needs it to update old asoc.
      But I don't think it would hurt something, as a temp asoc would
      always be freed after finishing processing cookie echo packet.
      Reported-by: default avatarJianwen Ji <jiji@redhat.com>
      Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
      Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
      Acked-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      7e062977
    • Xin Long's avatar
      sctp: fix stream update when processing dupcookie · 3ab21379
      Xin Long authored
      Since commit 3dbcc105 ("sctp: alloc stream info when initializing
      asoc"), stream and stream.out info are always alloced when creating
      an asoc.
      
      So it's not correct to check !asoc->stream before updating stream
      info when processing dupcookie, but would be better to check asoc
      state instead.
      
      Fixes: 3dbcc105 ("sctp: alloc stream info when initializing asoc")
      Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
      Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
      Acked-by: default avatarVlad Yasevich <vyasevich@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      3ab21379
  2. 23 May, 2017 7 commits
  3. 22 May, 2017 14 commits
    • Kees Cook's avatar
      efi-pstore: Fix write/erase id tracking · c10e8031
      Kees Cook authored
      Prior to the pstore interface refactoring, the "id" generated during
      a backend pstore_write() was only retained by the internal pstore
      inode tracking list. Additionally the "part" was ignored, so EFI
      would encode this in the id. This corrects the misunderstandings
      and correctly sets "id" during pstore_write(), and uses "part"
      directly during pstore_erase().
      Reported-by: default avatarMarta Lofstedt <marta.lofstedt@intel.com>
      Fixes: 76cc9580 ("pstore: Replace arguments for write() API")
      Fixes: a61072aa ("pstore: Replace arguments for erase() API")
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Tested-by: default avatarMarta Lofstedt <marta.lofstedt@intel.com>
      c10e8031
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 86ca984c
      Linus Torvalds authored
      Pull networking fixes from David Miller:
       "Mostly netfilter bug fixes in here, but we have some bits elsewhere as
        well.
      
         1) Don't do SNAT replies for non-NATed connections in IPVS, from
            Julian Anastasov.
      
         2) Don't delete conntrack helpers while they are still in use, from
            Liping Zhang.
      
         3) Fix zero padding in xtables's xt_data_to_user(), from Willem de
            Bruijn.
      
         4) Add proper RCU protection to nf_tables_dump_set() because we
            cannot guarantee that we hold the NFNL_SUBSYS_NFTABLES lock. From
            Liping Zhang.
      
         5) Initialize rcv_mss in tcp_disconnect(), from Wei Wang.
      
         6) smsc95xx devices can't handle IPV6 checksums fully, so don't
            advertise support for offloading them. From Nisar Sayed.
      
         7) Fix out-of-bounds access in __ip6_append_data(), from Eric
            Dumazet.
      
         8) Make atl2_probe() propagate the error code properly on failures,
            from Alexey Khoroshilov.
      
         9) arp_target[] in bond_check_params() is used uninitialized. This
            got changes from a global static to a local variable, which is how
            this mistake happened. Fix from Jarod Wilson.
      
        10) Fix fallout from unnecessary NULL check removal in cls_matchall,
            from Jiri Pirko. This is definitely brown paper bag territory..."
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (26 commits)
        net: sched: cls_matchall: fix null pointer dereference
        vsock: use new wait API for vsock_stream_sendmsg()
        bonding: fix randomly populated arp target array
        net: Make IP alignment calulations clearer.
        bonding: fix accounting of active ports in 3ad
        net: atheros: atl2: don't return zero on failure path in atl2_probe()
        ipv6: fix out of bound writes in __ip6_append_data()
        bridge: start hello_timer when enabling KERNEL_STP in br_stp_start
        smsc95xx: Support only IPv4 TCP/UDP csum offload
        arp: always override existing neigh entries with gratuitous ARP
        arp: postpone addr_type calculation to as late as possible
        arp: decompose is_garp logic into a separate function
        arp: fixed error in a comment
        tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0
        netfilter: xtables: fix build failure from COMPAT_XT_ALIGN outside CONFIG_COMPAT
        ebtables: arpreply: Add the standard target sanity check
        netfilter: nf_tables: revisit chain/object refcounting from elements
        netfilter: nf_tables: missing sanitization in data from userspace
        netfilter: nf_tables: can't assume lock is acquired when dumping set elems
        netfilter: synproxy: fix conntrackd interaction
        ...
      86ca984c
    • Jiri Pirko's avatar
      net: sched: cls_matchall: fix null pointer dereference · 2d76b2f8
      Jiri Pirko authored
      Since the head is guaranteed by the check above to be null, the call_rcu
      would explode. Remove the previously logically dead code that was made
      logically very much alive and kicking.
      
      Fixes: 985538ee ("net/sched: remove redundant null check on head")
      Signed-off-by: default avatarJiri Pirko <jiri@mellanox.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2d76b2f8
    • WANG Cong's avatar
      vsock: use new wait API for vsock_stream_sendmsg() · 499fde66
      WANG Cong authored
      As reported by Michal, vsock_stream_sendmsg() could still
      sleep at vsock_stream_has_space() after prepare_to_wait():
      
        vsock_stream_has_space
          vmci_transport_stream_has_space
            vmci_qpair_produce_free_space
              qp_lock
                qp_acquire_queue_mutex
                  mutex_lock
      
      Just switch to the new wait API like we did for commit
      d9dc8b0f ("net: fix sleeping for sk_wait_event()").
      Reported-by: default avatarMichal Kubecek <mkubecek@suse.cz>
      Cc: Stefan Hajnoczi <stefanha@redhat.com>
      Cc: Jorgen Hansen <jhansen@vmware.com>
      Cc: "Michael S. Tsirkin" <mst@redhat.com>
      Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
      Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
      Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      499fde66
    • Jarod Wilson's avatar
      bonding: fix randomly populated arp target array · 72ccc471
      Jarod Wilson authored
      In commit dc9c4d0f, the arp_target array moved from a static global
      to a local variable. By the nature of static globals, the array used to
      be initialized to all 0. At present, it's full of random data, which
      that gets interpreted as arp_target values, when none have actually been
      specified. Systems end up booting with spew along these lines:
      
      [   32.161783] IPv6: ADDRCONF(NETDEV_UP): lacp0: link is not ready
      [   32.168475] IPv6: ADDRCONF(NETDEV_UP): lacp0: link is not ready
      [   32.175089] 8021q: adding VLAN 0 to HW filter on device lacp0
      [   32.193091] IPv6: ADDRCONF(NETDEV_UP): lacp0: link is not ready
      [   32.204892] lacp0: Setting MII monitoring interval to 100
      [   32.211071] lacp0: Removing ARP target 216.124.228.17
      [   32.216824] lacp0: Removing ARP target 218.160.255.255
      [   32.222646] lacp0: Removing ARP target 185.170.136.184
      [   32.228496] lacp0: invalid ARP target 255.255.255.255 specified for removal
      [   32.236294] lacp0: option arp_ip_target: invalid value (-255.255.255.255)
      [   32.243987] lacp0: Removing ARP target 56.125.228.17
      [   32.249625] lacp0: Removing ARP target 218.160.255.255
      [   32.255432] lacp0: Removing ARP target 15.157.233.184
      [   32.261165] lacp0: invalid ARP target 255.255.255.255 specified for removal
      [   32.268939] lacp0: option arp_ip_target: invalid value (-255.255.255.255)
      [   32.276632] lacp0: Removing ARP target 16.0.0.0
      [   32.281755] lacp0: Removing ARP target 218.160.255.255
      [   32.287567] lacp0: Removing ARP target 72.125.228.17
      [   32.293165] lacp0: Removing ARP target 218.160.255.255
      [   32.298970] lacp0: Removing ARP target 8.125.228.17
      [   32.304458] lacp0: Removing ARP target 218.160.255.255
      
      None of these were actually specified as ARP targets, and the driver does
      seem to clean up the mess okay, but it's rather noisy and confusing, leaks
      values to userspace, and the 255.255.255.255 spew shows up even when debug
      prints are disabled.
      
      The fix: just zero out arp_target at init time.
      
      While we're in here, init arp_all_targets_value in the right place.
      
      Fixes: dc9c4d0f ("bonding: reduce scope of some global variables")
      CC: Mahesh Bandewar <maheshb@google.com>
      CC: Jay Vosburgh <j.vosburgh@gmail.com>
      CC: Veaceslav Falico <vfalico@gmail.com>
      CC: Andy Gospodarek <andy@greyhouse.net>
      CC: netdev@vger.kernel.org
      CC: stable@vger.kernel.org
      Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
      Acked-by: default avatarAndy Gospodarek <andy@greyhouse.net>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      72ccc471
    • Rafael J. Wysocki's avatar
      Merge branches 'pm-sleep' and 'powercap' · bb47e964
      Rafael J. Wysocki authored
      * pm-sleep:
        PM / hibernate: Declare variables as static
        RTC: rtc-cmos: Fix wakeup from suspend-to-idle
        PM / wakeup: Fix up wakeup_source_report_event()
      
      * powercap:
        PowerCap: Fix an error code in powercap_register_zone()
      bb47e964
    • Rafael J. Wysocki's avatar
      Merge branches 'acpi-button' and 'acpi-tools' · e3170cc0
      Rafael J. Wysocki authored
      * acpi-button:
        Revert "ACPI / button: Remove lid_init_state=method mode"
      
      * acpi-tools:
        tools/power/acpi: Add .gitignore file
      e3170cc0
    • Rafael J. Wysocki's avatar
      Merge branches 'intel_pstate', 'pm-cpufreq' and 'pm-cpufreq-sched' · 079c1812
      Rafael J. Wysocki authored
      * intel_pstate:
        cpufreq: intel_pstate: Document the current behavior and user interface
      
      * pm-cpufreq:
        cpufreq: dbx500: add a Kconfig symbol
      
      * pm-cpufreq-sched:
        cpufreq: schedutil: use now as reference when aggregating shared policy requests
      079c1812
    • David S. Miller's avatar
      net: Make IP alignment calulations clearer. · e4eda884
      David S. Miller authored
      The assignmnet:
      
      	ip_align = strict ? 2 : NET_IP_ALIGN;
      
      in compare_pkt_ptr_alignment() trips up Coverity because we can only
      get to this code when strict is true, therefore ip_align will always
      be 2 regardless of NET_IP_ALIGN's value.
      
      So just assign directly to '2' and explain the situation in the
      comment above.
      Reported-by: default avatar"Gustavo A. R. Silva" <garsilva@embeddedor.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      e4eda884
    • Jarod Wilson's avatar
      bonding: fix accounting of active ports in 3ad · 751da2a6
      Jarod Wilson authored
      As of 7bb11dc9 and 0622cab0, bond slaves in a 3ad bond are not
      removed from the aggregator when they are down, and the active slave count
      is NOT equal to number of ports in the aggregator, but rather the number
      of ports in the aggregator that are still enabled. The sysfs spew for
      bonding_show_ad_num_ports() has a comment that says "Show number of active
      802.3ad ports.", but it's currently showing total number of ports, both
      active and inactive. Remedy it by using the same logic introduced in
      0622cab0 in __bond_3ad_get_active_agg_info(), so sysfs, procfs and
      netlink all report the number of active ports. Note that this means that
      IFLA_BOND_AD_INFO_NUM_PORTS really means NUM_ACTIVE_PORTS instead of
      NUM_PORTS, and thus perhaps should be renamed for clarity.
      
      Lightly tested on a dual i40e lacp bond, simulating link downs with an ip
      link set dev <slave2> down, was able to produce the state where I could
      see both in the same aggregator, but a number of ports count of 1.
      
      MII Status: up
      Active Aggregator Info:
              Aggregator ID: 1
              Number of ports: 2 <---
      Slave Interface: ens10
      MII Status: up <---
      Aggregator ID: 1
      Slave Interface: ens11
      MII Status: up
      Aggregator ID: 1
      
      MII Status: up
      Active Aggregator Info:
              Aggregator ID: 1
              Number of ports: 1 <---
      Slave Interface: ens10
      MII Status: down <---
      Aggregator ID: 1
      Slave Interface: ens11
      MII Status: up
      Aggregator ID: 1
      
      CC: Jay Vosburgh <j.vosburgh@gmail.com>
      CC: Veaceslav Falico <vfalico@gmail.com>
      CC: Andy Gospodarek <andy@greyhouse.net>
      CC: netdev@vger.kernel.org
      Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      751da2a6
    • Alexey Khoroshilov's avatar
      net: atheros: atl2: don't return zero on failure path in atl2_probe() · bd703a15
      Alexey Khoroshilov authored
      If dma mask checks fail in atl2_probe(), it breaks off initialization,
      deallocates all resources, but returns zero.
      
      The patch adds proper error code return value and
      make error code setup unified.
      
      Found by Linux Driver Verification project (linuxtesting.org).
      Signed-off-by: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      bd703a15
    • Eric Dumazet's avatar
      ipv6: fix out of bound writes in __ip6_append_data() · 232cd35d
      Eric Dumazet authored
      Andrey Konovalov and idaifish@gmail.com reported crashes caused by
      one skb shared_info being overwritten from __ip6_append_data()
      
      Andrey program lead to following state :
      
      copy -4200 datalen 2000 fraglen 2040
      maxfraglen 2040 alloclen 2048 transhdrlen 0 offset 0 fraggap 6200
      
      The skb_copy_and_csum_bits(skb_prev, maxfraglen, data + transhdrlen,
      fraggap, 0); is overwriting skb->head and skb_shared_info
      
      Since we apparently detect this rare condition too late, move the
      code earlier to even avoid allocating skb and risking crashes.
      
      Once again, many thanks to Andrey and syzkaller team.
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
      Tested-by: default avatarAndrey Konovalov <andreyknvl@google.com>
      Reported-by: <idaifish@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      232cd35d
    • Linus Torvalds's avatar
      Linux 4.12-rc2 · 08332893
      Linus Torvalds authored
      08332893
    • Linus Torvalds's avatar
      x86: fix 32-bit case of __get_user_asm_u64() · 33c9e972
      Linus Torvalds authored
      The code to fetch a 64-bit value from user space was entirely buggered,
      and has been since the code was merged in early 2016 in commit
      b2f68038 ("x86/mm/32: Add support for 64-bit __get_user() on 32-bit
      kernels").
      
      Happily the buggered routine is almost certainly entirely unused, since
      the normal way to access user space memory is just with the non-inlined
      "get_user()", and the inlined version didn't even historically exist.
      
      The normal "get_user()" case is handled by external hand-written asm in
      arch/x86/lib/getuser.S that doesn't have either of these issues.
      
      There were two independent bugs in __get_user_asm_u64():
      
       - it still did the STAC/CLAC user space access marking, even though
         that is now done by the wrapper macros, see commit 11f1a4b9
         ("x86: reorganize SMAP handling in user space accesses").
      
         This didn't result in a semantic error, it just means that the
         inlined optimized version was hugely less efficient than the
         allegedly slower standard version, since the CLAC/STAC overhead is
         quite high on modern Intel CPU's.
      
       - the double register %eax/%edx was marked as an output, but the %eax
         part of it was touched early in the asm, and could thus clobber other
         inputs to the asm that gcc didn't expect it to touch.
      
         In particular, that meant that the generated code could look like
         this:
      
              mov    (%eax),%eax
              mov    0x4(%eax),%edx
      
         where the load of %edx obviously was _supposed_ to be from the 32-bit
         word that followed the source of %eax, but because %eax was
         overwritten by the first instruction, the source of %edx was
         basically random garbage.
      
      The fixes are trivial: remove the extraneous STAC/CLAC entries, and mark
      the 64-bit output as early-clobber to let gcc know that no inputs should
      alias with the output register.
      
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Benjamin LaHaise <bcrl@kvack.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: stable@kernel.org   # v4.8+
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      33c9e972
  4. 21 May, 2017 14 commits