1. 16 7月, 2018 1 次提交
  2. 23 6月, 2018 2 次提交
    • J
      bdi: Fix another oops in wb_workfn() · 3ee7e869
      Jan Kara 提交于
      syzbot is reporting NULL pointer dereference at wb_workfn() [1] due to
      wb->bdi->dev being NULL. And Dmitry confirmed that wb->state was
      WB_shutting_down after wb->bdi->dev became NULL. This indicates that
      unregister_bdi() failed to call wb_shutdown() on one of wb objects.
      
      The problem is in cgwb_bdi_unregister() which does cgwb_kill() and thus
      drops bdi's reference to wb structures before going through the list of
      wbs again and calling wb_shutdown() on each of them. This way the loop
      iterating through all wbs can easily miss a wb if that wb has already
      passed through cgwb_remove_from_bdi_list() called from wb_shutdown()
      from cgwb_release_workfn() and as a result fully shutdown bdi although
      wb_workfn() for this wb structure is still running. In fact there are
      also other ways cgwb_bdi_unregister() can race with
      cgwb_release_workfn() leading e.g. to use-after-free issues:
      
      CPU1                            CPU2
                                      cgwb_bdi_unregister()
                                        cgwb_kill(*slot);
      
      cgwb_release()
        queue_work(cgwb_release_wq, &wb->release_work);
      cgwb_release_workfn()
                                        wb = list_first_entry(&bdi->wb_list, ...)
                                        spin_unlock_irq(&cgwb_lock);
        wb_shutdown(wb);
        ...
        kfree_rcu(wb, rcu);
                                        wb_shutdown(wb); -> oops use-after-free
      
      We solve these issues by synchronizing writeback structure shutdown from
      cgwb_bdi_unregister() with cgwb_release_workfn() using a new mutex. That
      way we also no longer need synchronization using WB_shutting_down as the
      mutex provides it for CONFIG_CGROUP_WRITEBACK case and without
      CONFIG_CGROUP_WRITEBACK wb_shutdown() can be called only once from
      bdi_unregister().
      Reported-by: Nsyzbot <syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NJan Kara <jack@suse.cz>
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      3ee7e869
    • W
      rseq: Avoid infinite recursion when delivering SIGSEGV · 784e0300
      Will Deacon 提交于
      When delivering a signal to a task that is using rseq, we call into
      __rseq_handle_notify_resume() so that the registers pushed in the
      sigframe are updated to reflect the state of the restartable sequence
      (for example, ensuring that the signal returns to the abort handler if
      necessary).
      
      However, if the rseq management fails due to an unrecoverable fault when
      accessing userspace or certain combinations of RSEQ_CS_* flags, then we
      will attempt to deliver a SIGSEGV. This has the potential for infinite
      recursion if the rseq code continuously fails on signal delivery.
      
      Avoid this problem by using force_sigsegv() instead of force_sig(), which
      is explicitly designed to reset the SEGV handler to SIG_DFL in the case
      of a recursive fault. In doing so, remove rseq_signal_deliver() from the
      internal rseq API and have an optional struct ksignal * parameter to
      rseq_handle_notify_resume() instead.
      Signed-off-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: peterz@infradead.org
      Cc: paulmck@linux.vnet.ibm.com
      Cc: boqun.feng@gmail.com
      Link: https://lkml.kernel.org/r/1529664307-983-1-git-send-email-will.deacon@arm.com
      784e0300
  3. 22 6月, 2018 3 次提交
  4. 21 6月, 2018 7 次提交
  5. 20 6月, 2018 2 次提交
    • B
      ACPI / processor: Finish making acpi_processor_ppc_has_changed() void · a507a306
      Brian Norris 提交于
      Commit bca5f557 "ACPI / processor: Make acpi_processor_ppc_has_changed()
      void" changed one of the declarations of acpi_processor_ppc_has_changed()
      to return void, but the !CPU_FREQ version still returns int. Let's return
      void to be consistent.
      
      Fixes: bca5f557 "ACPI / processor: Make acpi_processor_ppc_has_changed() void"
      Signed-off-by: NBrian Norris <briannorris@chromium.org>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      a507a306
    • E
      net/ipv6: respect rcu grace period before freeing fib6_info · 9b0a8da8
      Eric Dumazet 提交于
      syzbot reported use after free that is caused by fib6_info being
      freed without a proper RCU grace period.
      
      CPU: 0 PID: 1407 Comm: udevd Not tainted 4.17.0+ #39
      Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
      Call Trace:
       <IRQ>
       __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
       __read_once_size include/linux/compiler.h:188 [inline]
       find_rr_leaf net/ipv6/route.c:705 [inline]
       rt6_select net/ipv6/route.c:761 [inline]
       fib6_table_lookup+0x12b7/0x14d0 net/ipv6/route.c:1823
       ip6_pol_route+0x1c2/0x1020 net/ipv6/route.c:1856
       ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2082
       fib6_rule_lookup+0x211/0x6d0 net/ipv6/fib6_rules.c:122
       ip6_route_output_flags+0x2c5/0x350 net/ipv6/route.c:2110
       ip6_route_output include/net/ip6_route.h:82 [inline]
       icmpv6_xrlim_allow net/ipv6/icmp.c:211 [inline]
       icmp6_send+0x147c/0x2da0 net/ipv6/icmp.c:535
       icmpv6_send+0x17a/0x300 net/ipv6/ip6_icmp.c:43
       ip6_link_failure+0xa5/0x790 net/ipv6/route.c:2244
       dst_link_failure include/net/dst.h:427 [inline]
       ndisc_error_report+0xd1/0x1c0 net/ipv6/ndisc.c:695
       neigh_invalidate+0x246/0x550 net/core/neighbour.c:892
       neigh_timer_handler+0xaf9/0xde0 net/core/neighbour.c:978
       call_timer_fn+0x230/0x940 kernel/time/timer.c:1326
       expire_timers kernel/time/timer.c:1363 [inline]
       __run_timers+0x79e/0xc50 kernel/time/timer.c:1666
       run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
       __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284
       invoke_softirq kernel/softirq.c:364 [inline]
       irq_exit+0x1d1/0x200 kernel/softirq.c:404
       exiting_irq arch/x86/include/asm/apic.h:527 [inline]
       smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052
       apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
       </IRQ>
      RIP: 0010:strlen+0x5e/0xa0 lib/string.c:482
      Code: 24 00 74 3b 48 bb 00 00 00 00 00 fc ff df 4c 89 e0 48 83 c0 01 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 0f b6 14 1a 38 ca 7f 04 <84> d2 75 23 80 38 00 75 de 48 83 c4 08 4c 29 e0 5b 41 5c 5d c3 48
      RSP: 0018:ffff8801af117850 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
      RAX: ffff880197f53bd0 RBX: dffffc0000000000 RCX: 0000000000000000
      RDX: 0000000000000000 RSI: ffffffff81c5b06c RDI: ffff880197f53bc0
      RBP: ffff8801af117868 R08: ffff88019a976540 R09: 0000000000000000
      R10: ffff88019a976540 R11: 0000000000000000 R12: ffff880197f53bc0
      R13: ffff880197f53bc0 R14: ffffffff899e4e90 R15: ffff8801d91c6a00
       strlen include/linux/string.h:267 [inline]
       getname_kernel+0x24/0x370 fs/namei.c:218
       open_exec+0x17/0x70 fs/exec.c:882
       load_elf_binary+0x968/0x5610 fs/binfmt_elf.c:780
       search_binary_handler+0x17d/0x570 fs/exec.c:1653
       exec_binprm fs/exec.c:1695 [inline]
       __do_execve_file.isra.35+0x16fe/0x2710 fs/exec.c:1819
       do_execveat_common fs/exec.c:1866 [inline]
       do_execve fs/exec.c:1883 [inline]
       __do_sys_execve fs/exec.c:1964 [inline]
       __se_sys_execve fs/exec.c:1959 [inline]
       __x64_sys_execve+0x8f/0xc0 fs/exec.c:1959
       do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
      RIP: 0033:0x7f1576a46207
      Code: 77 19 f4 48 89 d7 44 89 c0 0f 05 48 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 f7 d8 64 41 89 01 eb df b8 3b 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 02 f3 c3 48 8b 15 00 8c 2d 00 f7 d8 64 89 02
      RSP: 002b:00007ffff2784568 EFLAGS: 00000202 ORIG_RAX: 000000000000003b
      RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f1576a46207
      RDX: 0000000001215b10 RSI: 00007ffff2784660 RDI: 00007ffff2785670
      RBP: 0000000000625500 R08: 000000000000589c R09: 000000000000589c
      R10: 0000000000000000 R11: 0000000000000202 R12: 0000000001215b10
      R13: 0000000000000007 R14: 0000000001204250 R15: 0000000000000005
      
      Allocated by task 12188:
       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]
       fib6_info_alloc+0xbb/0x280 net/ipv6/ip6_fib.c:152
       ip6_route_info_create+0x782/0x2b50 net/ipv6/route.c:3013
       ip6_route_add+0x23/0xb0 net/ipv6/route.c:3154
       ipv6_route_ioctl+0x5a5/0x760 net/ipv6/route.c:3660
       inet6_ioctl+0x100/0x1f0 net/ipv6/af_inet6.c:546
       sock_do_ioctl+0xe4/0x3e0 net/socket.c:973
       sock_ioctl+0x30d/0x680 net/socket.c:1097
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:500 [inline]
       do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684
       ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
       __do_sys_ioctl fs/ioctl.c:708 [inline]
       __se_sys_ioctl fs/ioctl.c:706 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
       do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      Freed by task 1402:
       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
       fib6_info_destroy+0x29b/0x350 net/ipv6/ip6_fib.c:207
       fib6_info_release include/net/ip6_fib.h:286 [inline]
       __ip6_del_rt_siblings net/ipv6/route.c:3235 [inline]
       ip6_route_del+0x11c4/0x13b0 net/ipv6/route.c:3316
       ipv6_route_ioctl+0x616/0x760 net/ipv6/route.c:3663
       inet6_ioctl+0x100/0x1f0 net/ipv6/af_inet6.c:546
       sock_do_ioctl+0xe4/0x3e0 net/socket.c:973
       sock_ioctl+0x30d/0x680 net/socket.c:1097
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:500 [inline]
       do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684
       ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
       __do_sys_ioctl fs/ioctl.c:708 [inline]
       __se_sys_ioctl fs/ioctl.c:706 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
       do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      The buggy address belongs to the object at ffff8801b5df2580
       which belongs to the cache kmalloc-256 of size 256
      The buggy address is located 8 bytes inside of
       256-byte region [ffff8801b5df2580, ffff8801b5df2680)
      The buggy address belongs to the page:
      page:ffffea0006d77c80 count:1 mapcount:0 mapping:ffff8801da8007c0 index:0xffff8801b5df2e40
      flags: 0x2fffc0000000100(slab)
      raw: 02fffc0000000100 ffffea0006c5cc48 ffffea0007363308 ffff8801da8007c0
      raw: ffff8801b5df2e40 ffff8801b5df2080 0000000100000006 0000000000000000
      page dumped because: kasan: bad access detected
      
      Memory state around the buggy address:
       ffff8801b5df2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
       ffff8801b5df2500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
      > ffff8801b5df2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
       ffff8801b5df2600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
       ffff8801b5df2680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
      
      Fixes: a64efe14 ("net/ipv6: introduce fib6_info struct and helpers")
      Signed-off-by: NEric Dumazet <edumazet@google.com>
      Cc: David Ahern <dsahern@gmail.com>
      Reported-by: syzbot+9e6d75e3edef427ee888@syzkaller.appspotmail.com
      Acked-by: NDavid Ahern <dsahern@gmail.com>
      Tested-by: NDavid Ahern <dsahern@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9b0a8da8
  6. 19 6月, 2018 3 次提交
    • T
      pNFS/flexfiles: Don't tie up all the rpciod threads in resends · 42f86b44
      Trond Myklebust 提交于
      We do not want to have rpciod threads perform recursive calls into the
      RPC layer since that can deadlock. In particular, having to wait for
      a layoutget can be nasty... We want rather to defer scheduling those
      retries until we're in the rpc_release() callback, since that is
      called from the nfsiod workqueue.
      Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      42f86b44
    • R
      xen: share start flags between PV and PVH · 1fe83888
      Roger Pau Monne 提交于
      Use a global variable to store the start flags for both PV and PVH.
      This allows the xen_initial_domain macro to work properly on PVH.
      
      Note that ARM is also switched to use the new variable.
      Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
      Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
      Reviewed-by: NJuergen Gross <jgross@suse.com>
      Signed-off-by: NJuergen Gross <jgross@suse.com>
      1fe83888
    • B
      RDMA/core: Save kernel caller name when creating CQ using ib_create_cq() · 7350cdd0
      Bharat Potnuri 提交于
      Few kernel applications like SCST-iSER create CQ using ib_create_cq(),
      where accessing CQ structures using rdma restrack tool leads to below NULL
      pointer dereference. This patch saves caller kernel module name similar to
      ib_alloc_cq().
      
      BUG: unable to handle kernel NULL pointer dereference at           (null)
      IP: [<ffffffff8132ca70>] skip_spaces+0x30/0x30
      PGD 738bac067 PUD 8533f0067 PMD 0
      Oops: 0000 [#1] SMP
      R10: ffff88017fc03300 R11: 0000000000000246 R12: 0000000000000000
      R13: ffff88082fa5a668 R14: ffff88017475a000 R15: 0000000000000000
      FS:  00002b32726582c0(0000) GS:ffff88087fc40000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 0000000000000000 CR3: 00000008491a1000 CR4: 00000000003607e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
      Call Trace:
       [<ffffffffc05af69c>] ? fill_res_name_pid+0x7c/0x90 [ib_core]
       [<ffffffffc05af79f>] fill_res_cq_entry+0xef/0x170 [ib_core]
       [<ffffffffc05af4c4>] res_get_common_dumpit+0x3c4/0x480 [ib_core]
       [<ffffffffc05af5d3>] nldev_res_get_cq_dumpit+0x13/0x20 [ib_core]
       [<ffffffff815bc1e7>] netlink_dump+0x117/0x2e0
       [<ffffffff815bcb8b>] __netlink_dump_start+0x1ab/0x230
       [<ffffffffc059fead>] ibnl_rcv_msg+0x11d/0x1f0 [ib_core]
       [<ffffffffc05af5c0>] ? nldev_res_get_mr_dumpit+0x20/0x20 [ib_core]
       [<ffffffffc059fd90>] ? rdma_nl_multicast+0x30/0x30 [ib_core]
       [<ffffffff815bea49>] netlink_rcv_skb+0xa9/0xc0
       [<ffffffffc05a0018>] ibnl_rcv+0x98/0xb0 [ib_core]
       [<ffffffff815be132>] netlink_unicast+0xf2/0x1b0
       [<ffffffff815be50f>] netlink_sendmsg+0x31f/0x6a0
       [<ffffffff8156b580>] sock_sendmsg+0xb0/0xf0
       [<ffffffff816ace9e>] ? _raw_spin_unlock_bh+0x1e/0x20
       [<ffffffff8156f998>] ? release_sock+0x118/0x170
       [<ffffffff8156b731>] SYSC_sendto+0x121/0x1c0
       [<ffffffff81568340>] ? sock_alloc_file+0xa0/0x140
       [<ffffffff81221265>] ? __fd_install+0x25/0x60
       [<ffffffff8156c2ce>] SyS_sendto+0xe/0x10
       [<ffffffff816b6c2a>] system_call_fastpath+0x16/0x1b
      RIP  [<ffffffff8132ca70>] skip_spaces+0x30/0x30
      RSP <ffff88072be97760>
      CR2: 0000000000000000
      
      Cc: <stable@vger.kernel.org>
      Fixes: f66c8ba4 ("RDMA/core: Save kernel caller name when creating PD and CQ objects")
      Reviewed-by: NSteve Wise <swise@opengridcomputing.com>
      Signed-off-by: NPotnuri Bharat Teja <bharat@chelsio.com>
      Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
      Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>
      7350cdd0
  7. 17 6月, 2018 2 次提交
    • S
      firmware: dmi: Add access to the SKU ID string · b23908d3
      Simon Glass 提交于
      This is used in some systems from user space for determining the identity
      of the device.
      
      Expose this as a file so that that user-space tools don't need to read
      from /sys/firmware/dmi/tables/DMI
      Signed-off-by: NSimon Glass <sjg@chromium.org>
      Signed-off-by: NJean Delvare <jdelvare@suse.de>
      b23908d3
    • D
      atm: Preserve value of skb->truesize when accounting to vcc · 9bbe60a6
      David Woodhouse 提交于
      ATM accounts for in-flight TX packets in sk_wmem_alloc of the VCC on
      which they are to be sent. But it doesn't take ownership of those
      packets from the sock (if any) which originally owned them. They should
      remain owned by their actual sender until they've left the box.
      
      There's a hack in pskb_expand_head() to avoid adjusting skb->truesize
      for certain skbs, precisely to avoid messing up sk_wmem_alloc
      accounting. Ideally that hack would cover the ATM use case too, but it
      doesn't — skbs which aren't owned by any sock, for example PPP control
      frames, still get their truesize adjusted when the low-level ATM driver
      adds headroom.
      
      This has always been an issue, it seems. The truesize of a packet
      increases, and sk_wmem_alloc on the VCC goes negative. But this wasn't
      for normal traffic, only for control frames. So I think we just got away
      with it, and we probably needed to send 2GiB of LCP echo frames before
      the misaccounting would ever have caused a problem and caused
      atm_may_send() to start refusing packets.
      
      Commit 14afee4b ("net: convert sock.sk_wmem_alloc from atomic_t to
      refcount_t") did exactly what it was intended to do, and turned this
      mostly-theoretical problem into a real one, causing PPPoATM to fail
      immediately as sk_wmem_alloc underflows and atm_may_send() *immediately*
      starts refusing to allow new packets.
      
      The least intrusive solution to this problem is to stash the value of
      skb->truesize that was accounted to the VCC, in a new member of the
      ATM_SKB(skb) structure. Then in atm_pop_raw() subtract precisely that
      value instead of the then-current value of skb->truesize.
      
      Fixes: 158f323b ("net: adjust skb->truesize in pskb_expand_head()")
      Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>
      Tested-by: NKevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9bbe60a6
  8. 16 6月, 2018 6 次提交
  9. 15 6月, 2018 9 次提交
  10. 14 6月, 2018 4 次提交
    • C
      blk-mq: remove blk_mq_tagset_iter · e6c3456a
      Christoph Hellwig 提交于
      Unused now that nvme stopped using it.
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      Reviewed-by: NJens Axboe <axboe@kernel.dk>
      e6c3456a
    • C
      blk-mq: don't time out requests again that are in the timeout handler · da661267
      Christoph Hellwig 提交于
      We can currently call the timeout handler again on a request that has
      already been handed over to the timeout handler.  Prevent that with a new
      flag.
      
      Fixes: 12f5b931 ("blk-mq: Remove generation seqeunce")
      Reported-by: NAndrew Randrianasulu <randrianasulu@gmail.com>
      Tested-by: NAndrew Randrianasulu <randrianasulu@gmail.com>
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NJens Axboe <axboe@kernel.dk>
      da661267
    • C
      dma-mapping: move all DMA mapping code to kernel/dma · cf65a0f6
      Christoph Hellwig 提交于
      Currently the code is split over various files with dma- prefixes in the
      lib/ and drives/base directories, and the number of files keeps growing.
      Move them into a single directory to keep the code together and remove
      the file name prefixes.  To match the irq infrastructure this directory
      is placed under the kernel/ directory.
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      cf65a0f6
    • L
      Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables · 050e9baa
      Linus Torvalds 提交于
      The changes to automatically test for working stack protector compiler
      support in the Kconfig files removed the special STACKPROTECTOR_AUTO
      option that picked the strongest stack protector that the compiler
      supported.
      
      That was all a nice cleanup - it makes no sense to have the AUTO case
      now that the Kconfig phase can just determine the compiler support
      directly.
      
      HOWEVER.
      
      It also meant that doing "make oldconfig" would now _disable_ the strong
      stackprotector if you had AUTO enabled, because in a legacy config file,
      the sane stack protector configuration would look like
      
        CONFIG_HAVE_CC_STACKPROTECTOR=y
        # CONFIG_CC_STACKPROTECTOR_NONE is not set
        # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
        # CONFIG_CC_STACKPROTECTOR_STRONG is not set
        CONFIG_CC_STACKPROTECTOR_AUTO=y
      
      and when you ran this through "make oldconfig" with the Kbuild changes,
      it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
      been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
      CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
      used to be disabled (because it was really enabled by AUTO), and would
      disable it in the new config, resulting in:
      
        CONFIG_HAVE_CC_STACKPROTECTOR=y
        CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
        CONFIG_CC_STACKPROTECTOR=y
        # CONFIG_CC_STACKPROTECTOR_STRONG is not set
        CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
      
      That's dangerously subtle - people could suddenly find themselves with
      the weaker stack protector setup without even realizing.
      
      The solution here is to just rename not just the old RECULAR stack
      protector option, but also the strong one.  This does that by just
      removing the CC_ prefix entirely for the user choices, because it really
      is not about the compiler support (the compiler support now instead
      automatially impacts _visibility_ of the options to users).
      
      This results in "make oldconfig" actually asking the user for their
      choice, so that we don't have any silent subtle security model changes.
      The end result would generally look like this:
      
        CONFIG_HAVE_CC_STACKPROTECTOR=y
        CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
        CONFIG_STACKPROTECTOR=y
        CONFIG_STACKPROTECTOR_STRONG=y
        CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
      
      where the "CC_" versions really are about internal compiler
      infrastructure, not the user selections.
      Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      050e9baa
  11. 13 6月, 2018 1 次提交