1. 07 8月, 2017 1 次提交
  2. 05 8月, 2017 1 次提交
  3. 03 8月, 2017 6 次提交
    • K
      mm: allow page_cache_get_speculative in interrupt context · 1ee1c3f5
      Kan Liang 提交于
      Kernel panic when calling the IRQ-safe __get_user_pages_fast in NMI
      handler.
      
      The bug was introduced by commit 2947ba05 ("x86/mm/gup: Switch GUP
      to the generic get_user_page_fast() implementation").
      
      The original x86 __get_user_page_fast used plain get_page() or
      page_ref_add().  However, the generic __get_user_page_fast uses
      page_cache_get_speculative(), which has VM_BUG_ON(in_interrupt()).
      
      There is no reason to prevent page_cache_get_speculative from using in
      interrupt context.  According to the author, putting a BUG_ON there is
      just because the code is not verifying correctness of interrupt races.
      I did some tests in interrupt context.  There is no issue found.
      
      Removing VM_BUG_ON(in_interrupt()) for page_cache_get_speculative().
      
      Link: http://lkml.kernel.org/r/1501609146-59730-1-git-send-email-kan.liang@intel.com
      Fixes: 2947ba05 ("x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation")
      Signed-off-by: NKan Liang <kan.liang@intel.com>
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Ying Huang <ying.huang@intel.com>
      Cc: Nicholas Piggin <npiggin@gmail.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1ee1c3f5
    • D
      cpuset: fix a deadlock due to incomplete patching of cpusets_enabled() · 89affbf5
      Dima Zavin 提交于
      In codepaths that use the begin/retry interface for reading
      mems_allowed_seq with irqs disabled, there exists a race condition that
      stalls the patch process after only modifying a subset of the
      static_branch call sites.
      
      This problem manifested itself as a deadlock in the slub allocator,
      inside get_any_partial.  The loop reads mems_allowed_seq value (via
      read_mems_allowed_begin), performs the defrag operation, and then
      verifies the consistency of mem_allowed via the read_mems_allowed_retry
      and the cookie returned by xxx_begin.
      
      The issue here is that both begin and retry first check if cpusets are
      enabled via cpusets_enabled() static branch.  This branch can be
      rewritted dynamically (via cpuset_inc) if a new cpuset is created.  The
      x86 jump label code fully synchronizes across all CPUs for every entry
      it rewrites.  If it rewrites only one of the callsites (specifically the
      one in read_mems_allowed_retry) and then waits for the
      smp_call_function(do_sync_core) to complete while a CPU is inside the
      begin/retry section with IRQs off and the mems_allowed value is changed,
      we can hang.
      
      This is because begin() will always return 0 (since it wasn't patched
      yet) while retry() will test the 0 against the actual value of the seq
      counter.
      
      The fix is to use two different static keys: one for begin
      (pre_enable_key) and one for retry (enable_key).  In cpuset_inc(), we
      first bump the pre_enable key to ensure that cpuset_mems_allowed_begin()
      always return a valid seqcount if are enabling cpusets.  Similarly, when
      disabling cpusets via cpuset_dec(), we first ensure that callers of
      cpuset_mems_allowed_retry() will start ignoring the seqcount value
      before we let cpuset_mems_allowed_begin() return 0.
      
      The relevant stack traces of the two stuck threads:
      
        CPU: 1 PID: 1415 Comm: mkdir Tainted: G L  4.9.36-00104-g540c51286237 #4
        Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017
        task: ffff8817f9c28000 task.stack: ffffc9000ffa4000
        RIP: smp_call_function_many+0x1f9/0x260
        Call Trace:
          smp_call_function+0x3b/0x70
          on_each_cpu+0x2f/0x90
          text_poke_bp+0x87/0xd0
          arch_jump_label_transform+0x93/0x100
          __jump_label_update+0x77/0x90
          jump_label_update+0xaa/0xc0
          static_key_slow_inc+0x9e/0xb0
          cpuset_css_online+0x70/0x2e0
          online_css+0x2c/0xa0
          cgroup_apply_control_enable+0x27f/0x3d0
          cgroup_mkdir+0x2b7/0x420
          kernfs_iop_mkdir+0x5a/0x80
          vfs_mkdir+0xf6/0x1a0
          SyS_mkdir+0xb7/0xe0
          entry_SYSCALL_64_fastpath+0x18/0xad
      
        ...
      
        CPU: 2 PID: 1 Comm: init Tainted: G L  4.9.36-00104-g540c51286237 #4
        Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017
        task: ffff8818087c0000 task.stack: ffffc90000030000
        RIP: int3+0x39/0x70
        Call Trace:
          <#DB> ? ___slab_alloc+0x28b/0x5a0
          <EOE> ? copy_process.part.40+0xf7/0x1de0
          __slab_alloc.isra.80+0x54/0x90
          copy_process.part.40+0xf7/0x1de0
          copy_process.part.40+0xf7/0x1de0
          kmem_cache_alloc_node+0x8a/0x280
          copy_process.part.40+0xf7/0x1de0
          _do_fork+0xe7/0x6c0
          _raw_spin_unlock_irq+0x2d/0x60
          trace_hardirqs_on_caller+0x136/0x1d0
          entry_SYSCALL_64_fastpath+0x5/0xad
          do_syscall_64+0x27/0x350
          SyS_clone+0x19/0x20
          do_syscall_64+0x60/0x350
          entry_SYSCALL64_slow_path+0x25/0x25
      
      Link: http://lkml.kernel.org/r/20170731040113.14197-1-dmitriyz@waymo.com
      Fixes: 46e700ab ("mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled")
      Signed-off-by: NDima Zavin <dmitriyz@waymo.com>
      Reported-by: NCliff Spradlin <cspradlin@waymo.com>
      Acked-by: NVlastimil Babka <vbabka@suse.cz>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Christopher Lameter <cl@linux.com>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Pekka Enberg <penberg@kernel.org>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      89affbf5
    • J
      kthread: fix documentation build warning · d16977f3
      Jonathan Corbet 提交于
      The kerneldoc comment for kthread_create() had an incorrect argument
      name, leading to a warning in the docs build.
      
      Correct it, and make one more small step toward a warning-free build.
      
      Link: http://lkml.kernel.org/r/20170724135916.7f486c6f@lwn.netSigned-off-by: NJonathan Corbet <corbet@lwn.net>
      Cc: Randy Dunlap <rdunlap@infradead.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d16977f3
    • M
      mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries · 3ea27719
      Mel Gorman 提交于
      Nadav Amit identified a theoritical race between page reclaim and
      mprotect due to TLB flushes being batched outside of the PTL being held.
      
      He described the race as follows:
      
              CPU0                            CPU1
              ----                            ----
                                              user accesses memory using RW PTE
                                              [PTE now cached in TLB]
              try_to_unmap_one()
              ==> ptep_get_and_clear()
              ==> set_tlb_ubc_flush_pending()
                                              mprotect(addr, PROT_READ)
                                              ==> change_pte_range()
                                              ==> [ PTE non-present - no flush ]
      
                                              user writes using cached RW PTE
              ...
      
              try_to_unmap_flush()
      
      The same type of race exists for reads when protecting for PROT_NONE and
      also exists for operations that can leave an old TLB entry behind such
      as munmap, mremap and madvise.
      
      For some operations like mprotect, it's not necessarily a data integrity
      issue but it is a correctness issue as there is a window where an
      mprotect that limits access still allows access.  For munmap, it's
      potentially a data integrity issue although the race is massive as an
      munmap, mmap and return to userspace must all complete between the
      window when reclaim drops the PTL and flushes the TLB.  However, it's
      theoritically possible so handle this issue by flushing the mm if
      reclaim is potentially currently batching TLB flushes.
      
      Other instances where a flush is required for a present pte should be ok
      as either the page lock is held preventing parallel reclaim or a page
      reference count is elevated preventing a parallel free leading to
      corruption.  In the case of page_mkclean there isn't an obvious path
      that userspace could take advantage of without using the operations that
      are guarded by this patch.  Other users such as gup as a race with
      reclaim looks just at PTEs.  huge page variants should be ok as they
      don't race with reclaim.  mincore only looks at PTEs.  userfault also
      should be ok as if a parallel reclaim takes place, it will either fault
      the page back in or read some of the data before the flush occurs
      triggering a fault.
      
      Note that a variant of this patch was acked by Andy Lutomirski but this
      was for the x86 parts on top of his PCID work which didn't make the 4.13
      merge window as expected.  His ack is dropped from this version and
      there will be a follow-on patch on top of PCID that will include his
      ack.
      
      [akpm@linux-foundation.org: tweak comments]
      [akpm@linux-foundation.org: fix spello]
      Link: http://lkml.kernel.org/r/20170717155523.emckq2esjro6hf3z@suse.deReported-by: NNadav Amit <nadav.amit@gmail.com>
      Signed-off-by: NMel Gorman <mgorman@suse.de>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: <stable@vger.kernel.org>	[v4.4+]
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3ea27719
    • P
      KVM: avoid using rcu_dereference_protected · 3898da94
      Paolo Bonzini 提交于
      During teardown, accesses to memslots and buses are using
      rcu_dereference_protected with an always-true condition because
      these accesses are done outside the usual mutexes.  This
      is because the last reference is gone and there cannot be any
      concurrent modifications, but rcu_dereference_protected is
      ugly and unobvious.
      
      Instead, check the refcount in kvm_get_bus and __kvm_memslots.
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      3898da94
    • I
      net/mlx4_en: Fix wrong indication of Wake-on-LAN (WoL) support · c994f778
      Inbar Karmy 提交于
      Currently when WoL is supported but disabled, ethtool reports:
      "Supports Wake-on: d".
      Fix the indication of Wol support, so that the indication
      remains "g" all the time if the NIC supports WoL.
      
      Tested:
      As accepted, when NIC supports WoL- ethtool reports:
      	Supports Wake-on: g
      	Wake-on: d
      when NIC doesn't support WoL- ethtool reports:
              Supports Wake-on: d
              Wake-on: d
      
      Fixes: 14c07b13 ("mlx4: Wake on LAN support")
      Signed-off-by: NInbar Karmy <inbark@mellanox.com>
      Signed-off-by: NTariq Toukan <tariqt@mellanox.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c994f778
  4. 02 8月, 2017 3 次提交
    • B
      mtd: nand: Declare tBERS, tR and tPROG as u64 to avoid integer overflow · 6d292310
      Boris Brezillon 提交于
      All timings in nand_sdr_timings are expressed in picoseconds but some
      of them may not fit in an u32.
      Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
      Fixes: 204e7ecd ("mtd: nand: Add a few more timings to nand_sdr_timings")
      Reported-by: NAlexander Dahl <ada@thorsis.com>
      Cc: <stable@vger.kernel.org>
      Reviewed-by: NAlexander Dahl <ada@thorsis.com>
      Tested-by: NAlexander Dahl <ada@thorsis.com>
      Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
      6d292310
    • G
      ptp: introduce ptp auxiliary worker · d9535cb7
      Grygorii Strashko 提交于
      Many PTP drivers required to perform some asynchronous or periodic work,
      like periodically handling PHC counter overflow or handle delayed timestamp
      for RX/TX network packets. In most of the cases, such work is implemented
      using workqueues. Unfortunately, Kernel workqueues might introduce
      significant delay in work scheduling under high system load and on -RT,
      which could cause misbehavior of PTP drivers due to internal counter
      overflow, for example, and there is no way to tune its execution policy and
      priority manuallly.
      
      Hence, The kthread_worker can be used insted of workqueues, as it create
      separte named kthread for each worker and its its execution policy and
      priority can be configured using chrt tool.
      
      This prblem was reported for two drivers TI CPSW CPTS and dp83640, so
      instead of modifying each of these driver it was proposed to add PTP
      auxiliary worker to the PHC subsystem.
      
      The patch adds PTP auxiliary worker in PHC subsystem using kthread_worker
      and kthread_delayed_work and introduces two new PHC subsystem APIs:
      
      - long (*do_aux_work)(struct ptp_clock_info *ptp) callback in
      ptp_clock_info structure, which driver should assign if it require to
      perform asynchronous or periodic work. Driver should return the delay of
      the PTP next auxiliary work scheduling time (>=0) or negative value in case
      further scheduling is not required.
      
      - int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay) which
      allows schedule PTP auxiliary work.
      
      The name of kthread_worker thread corresponds PTP PHC device name "ptp%d".
      Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d9535cb7
    • T
      NFSv4: Fix EXCHANGE_ID corrupt verifier issue · fd40559c
      Trond Myklebust 提交于
      The verifier is allocated on the stack, but the EXCHANGE_ID RPC call was
      changed to be asynchronous by commit 8d89bd70. If we interrrupt
      the call to rpc_wait_for_completion_task(), we can therefore end up
      transmitting random stack contents in lieu of the verifier.
      
      Fixes: 8d89bd70 ("NFS setup async exchange_id")
      Cc: stable@vger.kernel.org # v4.9+
      Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
      fd40559c
  5. 01 8月, 2017 3 次提交
  6. 31 7月, 2017 1 次提交
  7. 27 7月, 2017 9 次提交
  8. 26 7月, 2017 3 次提交
    • M
      net: phy: Remove trailing semicolon in macro definition · 2eaa38d9
      Marc Gonzalez 提交于
      Commit e5a03bfd ("phy: Add an mdio_device structure")
      introduced a spurious trailing semicolon. Remove it.
      Signed-off-by: NMarc Gonzalez <marc_gonzalez@sigmadesigns.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2eaa38d9
    • T
      workqueue: implicit ordered attribute should be overridable · 0a94efb5
      Tejun Heo 提交于
      5c0338c6 ("workqueue: restore WQ_UNBOUND/max_active==1 to be
      ordered") automatically enabled ordered attribute for unbound
      workqueues w/ max_active == 1.  Because ordered workqueues reject
      max_active and some attribute changes, this implicit ordered mode
      broke cases where the user creates an unbound workqueue w/ max_active
      == 1 and later explicitly changes the related attributes.
      
      This patch distinguishes explicit and implicit ordered setting and
      overrides from attribute changes if implict.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Fixes: 5c0338c6 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
      0a94efb5
    • J
      nvme-fc: revise TRADDR parsing · 9c5358e1
      James Smart 提交于
      The FC-NVME spec hasn't locked down on the format string for TRADDR.
      Currently the spec is lobbying for "nn-<16hexdigits>:pn-<16hexdigits>"
      where the wwn's are hex values but not prefixed by 0x.
      
      Most implementations so far expect a string format of
      "nn-0x<16hexdigits>:pn-0x<16hexdigits>" to be used. The transport
      uses the match_u64 parser which requires a leading 0x prefix to set
      the base properly. If it's not there, a match will either fail or return
      a base 10 value.
      
      The resolution in T11 is pushing out. Therefore, to fix things now and
      to cover any eventuality and any implementations already in the field,
      this patch adds support for both formats.
      
      The change consists of replacing the token matching routine with a
      routine that validates the fixed string format, and then builds
      a local copy of the hex name with a 0x prefix before calling
      the system parser.
      
      Note: the same parser routine exists in both the initiator and target
      transports. Given this is about the only "shared" item, we chose to
      replicate rather than create an interdendency on some shared code.
      Signed-off-by: NJames Smart <james.smart@broadcom.com>
      Signed-off-by: NChristoph Hellwig <hch@lst.de>
      9c5358e1
  9. 25 7月, 2017 2 次提交
  10. 24 7月, 2017 1 次提交
  11. 21 7月, 2017 2 次提交
    • T
    • D
      bpf: fix mixed signed/unsigned derived min/max value bounds · 4cabc5b1
      Daniel Borkmann 提交于
      Edward reported that there's an issue in min/max value bounds
      tracking when signed and unsigned compares both provide hints
      on limits when having unknown variables. E.g. a program such
      as the following should have been rejected:
      
         0: (7a) *(u64 *)(r10 -8) = 0
         1: (bf) r2 = r10
         2: (07) r2 += -8
         3: (18) r1 = 0xffff8a94cda93400
         5: (85) call bpf_map_lookup_elem#1
         6: (15) if r0 == 0x0 goto pc+7
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp
         7: (7a) *(u64 *)(r10 -16) = -8
         8: (79) r1 = *(u64 *)(r10 -16)
         9: (b7) r2 = -1
        10: (2d) if r1 > r2 goto pc+3
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=0
        R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp
        11: (65) if r1 s> 0x1 goto pc+2
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=0,max_value=1
        R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp
        12: (0f) r0 += r1
        13: (72) *(u8 *)(r0 +0) = 0
        R0=map_value_adj(ks=8,vs=8,id=0),min_value=0,max_value=1 R1=inv,min_value=0,max_value=1
        R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp
        14: (b7) r0 = 0
        15: (95) exit
      
      What happens is that in the first part ...
      
         8: (79) r1 = *(u64 *)(r10 -16)
         9: (b7) r2 = -1
        10: (2d) if r1 > r2 goto pc+3
      
      ... r1 carries an unsigned value, and is compared as unsigned
      against a register carrying an immediate. Verifier deduces in
      reg_set_min_max() that since the compare is unsigned and operation
      is greater than (>), that in the fall-through/false case, r1's
      minimum bound must be 0 and maximum bound must be r2. Latter is
      larger than the bound and thus max value is reset back to being
      'invalid' aka BPF_REGISTER_MAX_RANGE. Thus, r1 state is now
      'R1=inv,min_value=0'. The subsequent test ...
      
        11: (65) if r1 s> 0x1 goto pc+2
      
      ... is a signed compare of r1 with immediate value 1. Here,
      verifier deduces in reg_set_min_max() that since the compare
      is signed this time and operation is greater than (>), that
      in the fall-through/false case, we can deduce that r1's maximum
      bound must be 1, meaning with prior test, we result in r1 having
      the following state: R1=inv,min_value=0,max_value=1. Given that
      the actual value this holds is -8, the bounds are wrongly deduced.
      When this is being added to r0 which holds the map_value(_adj)
      type, then subsequent store access in above case will go through
      check_mem_access() which invokes check_map_access_adj(), that
      will then probe whether the map memory is in bounds based
      on the min_value and max_value as well as access size since
      the actual unknown value is min_value <= x <= max_value; commit
      fce366a9 ("bpf, verifier: fix alu ops against map_value{,
      _adj} register types") provides some more explanation on the
      semantics.
      
      It's worth to note in this context that in the current code,
      min_value and max_value tracking are used for two things, i)
      dynamic map value access via check_map_access_adj() and since
      commit 06c1c049 ("bpf: allow helpers access to variable memory")
      ii) also enforced at check_helper_mem_access() when passing a
      memory address (pointer to packet, map value, stack) and length
      pair to a helper and the length in this case is an unknown value
      defining an access range through min_value/max_value in that
      case. The min_value/max_value tracking is /not/ used in the
      direct packet access case to track ranges. However, the issue
      also affects case ii), for example, the following crafted program
      based on the same principle must be rejected as well:
      
         0: (b7) r2 = 0
         1: (bf) r3 = r10
         2: (07) r3 += -512
         3: (7a) *(u64 *)(r10 -16) = -8
         4: (79) r4 = *(u64 *)(r10 -16)
         5: (b7) r6 = -1
         6: (2d) if r4 > r6 goto pc+5
        R1=ctx R2=imm0,min_value=0,max_value=0,min_align=2147483648 R3=fp-512
        R4=inv,min_value=0 R6=imm-1,max_value=18446744073709551615,min_align=1 R10=fp
         7: (65) if r4 s> 0x1 goto pc+4
        R1=ctx R2=imm0,min_value=0,max_value=0,min_align=2147483648 R3=fp-512
        R4=inv,min_value=0,max_value=1 R6=imm-1,max_value=18446744073709551615,min_align=1
        R10=fp
         8: (07) r4 += 1
         9: (b7) r5 = 0
        10: (6a) *(u16 *)(r10 -512) = 0
        11: (85) call bpf_skb_load_bytes#26
        12: (b7) r0 = 0
        13: (95) exit
      
      Meaning, while we initialize the max_value stack slot that the
      verifier thinks we access in the [1,2] range, in reality we
      pass -7 as length which is interpreted as u32 in the helper.
      Thus, this issue is relevant also for the case of helper ranges.
      Resetting both bounds in check_reg_overflow() in case only one
      of them exceeds limits is also not enough as similar test can be
      created that uses values which are within range, thus also here
      learned min value in r1 is incorrect when mixed with later signed
      test to create a range:
      
         0: (7a) *(u64 *)(r10 -8) = 0
         1: (bf) r2 = r10
         2: (07) r2 += -8
         3: (18) r1 = 0xffff880ad081fa00
         5: (85) call bpf_map_lookup_elem#1
         6: (15) if r0 == 0x0 goto pc+7
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp
         7: (7a) *(u64 *)(r10 -16) = -8
         8: (79) r1 = *(u64 *)(r10 -16)
         9: (b7) r2 = 2
        10: (3d) if r2 >= r1 goto pc+3
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3
        R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp
        11: (65) if r1 s> 0x4 goto pc+2
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0
        R1=inv,min_value=3,max_value=4 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp
        12: (0f) r0 += r1
        13: (72) *(u8 *)(r0 +0) = 0
        R0=map_value_adj(ks=8,vs=8,id=0),min_value=3,max_value=4
        R1=inv,min_value=3,max_value=4 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp
        14: (b7) r0 = 0
        15: (95) exit
      
      This leaves us with two options for fixing this: i) to invalidate
      all prior learned information once we switch signed context, ii)
      to track min/max signed and unsigned boundaries separately as
      done in [0]. (Given latter introduces major changes throughout
      the whole verifier, it's rather net-next material, thus this
      patch follows option i), meaning we can derive bounds either
      from only signed tests or only unsigned tests.) There is still the
      case of adjust_reg_min_max_vals(), where we adjust bounds on ALU
      operations, meaning programs like the following where boundaries
      on the reg get mixed in context later on when bounds are merged
      on the dst reg must get rejected, too:
      
         0: (7a) *(u64 *)(r10 -8) = 0
         1: (bf) r2 = r10
         2: (07) r2 += -8
         3: (18) r1 = 0xffff89b2bf87ce00
         5: (85) call bpf_map_lookup_elem#1
         6: (15) if r0 == 0x0 goto pc+6
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp
         7: (7a) *(u64 *)(r10 -16) = -8
         8: (79) r1 = *(u64 *)(r10 -16)
         9: (b7) r2 = 2
        10: (3d) if r2 >= r1 goto pc+2
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3
        R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp
        11: (b7) r7 = 1
        12: (65) if r7 s> 0x0 goto pc+2
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3
        R2=imm2,min_value=2,max_value=2,min_align=2 R7=imm1,max_value=0 R10=fp
        13: (b7) r0 = 0
        14: (95) exit
      
        from 12 to 15: R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0
        R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R7=imm1,min_value=1 R10=fp
        15: (0f) r7 += r1
        16: (65) if r7 s> 0x4 goto pc+2
        R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3
        R2=imm2,min_value=2,max_value=2,min_align=2 R7=inv,min_value=4,max_value=4 R10=fp
        17: (0f) r0 += r7
        18: (72) *(u8 *)(r0 +0) = 0
        R0=map_value_adj(ks=8,vs=8,id=0),min_value=4,max_value=4 R1=inv,min_value=3
        R2=imm2,min_value=2,max_value=2,min_align=2 R7=inv,min_value=4,max_value=4 R10=fp
        19: (b7) r0 = 0
        20: (95) exit
      
      Meaning, in adjust_reg_min_max_vals() we must also reset range
      values on the dst when src/dst registers have mixed signed/
      unsigned derived min/max value bounds with one unbounded value
      as otherwise they can be added together deducing false boundaries.
      Once both boundaries are established from either ALU ops or
      compare operations w/o mixing signed/unsigned insns, then they
      can safely be added to other regs also having both boundaries
      established. Adding regs with one unbounded side to a map value
      where the bounded side has been learned w/o mixing ops is
      possible, but the resulting map value won't recover from that,
      meaning such op is considered invalid on the time of actual
      access. Invalid bounds are set on the dst reg in case i) src reg,
      or ii) in case dst reg already had them. The only way to recover
      would be to perform i) ALU ops but only 'add' is allowed on map
      value types or ii) comparisons, but these are disallowed on
      pointers in case they span a range. This is fine as only BPF_JEQ
      and BPF_JNE may be performed on PTR_TO_MAP_VALUE_OR_NULL registers
      which potentially turn them into PTR_TO_MAP_VALUE type depending
      on the branch, so only here min/max value cannot be invalidated
      for them.
      
      In terms of state pruning, value_from_signed is considered
      as well in states_equal() when dealing with adjusted map values.
      With regards to breaking existing programs, there is a small
      risk, but use-cases are rather quite narrow where this could
      occur and mixing compares probably unlikely.
      
      Joint work with Josef and Edward.
      
        [0] https://lists.iovisor.org/pipermail/iovisor-dev/2017-June/000822.html
      
      Fixes: 48461135 ("bpf: allow access into map value arrays")
      Reported-by: NEdward Cree <ecree@solarflare.com>
      Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      Signed-off-by: NEdward Cree <ecree@solarflare.com>
      Signed-off-by: NJosef Bacik <jbacik@fb.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4cabc5b1
  12. 20 7月, 2017 4 次提交
  13. 18 7月, 2017 4 次提交