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  1. Sep 15, 2022
  2. Sep 05, 2022
    • Greg Kroah-Hartman's avatar
    • Kuniyuki Iwashima's avatar
      kprobes: don't call disarm_kprobe() for disabled kprobes · 19cd6307
      Kuniyuki Iwashima authored
      commit 9c80e799 upstream.
      
      The assumption in __disable_kprobe() is wrong, and it could try to disarm
      an already disarmed kprobe and fire the WARN_ONCE() below. [0]  We can
      easily reproduce this issue.
      
      1. Write 0 to /sys/kernel/debug/kprobes/enabled.
      
        # echo 0 > /sys/kernel/debug/kprobes/enabled
      
      2. Run execsnoop.  At this time, one kprobe is disabled.
      
        # /usr/share/bcc/tools/execsnoop &
        [1] 2460
        PCOMM            PID    PPID   RET ARGS
      
        # cat /sys/kernel/debug/kprobes/list
        ffffffff91345650  r  __x64_sys_execve+0x0    [FTRACE]
        ffffffff91345650  k  __x64_sys_execve+0x0    [DISABLED][FTRACE]
      
      3. Write 1 to /sys/kernel/debug/kprobes/enabled, which changes
         kprobes_all_disarmed to false but does not arm the disabled kprobe.
      
        # echo 1 > /sys/kernel/debug/kprobes/enabled
      
        # cat /sys/kernel/debug/kprobes/list
        ffffffff91345650  r  __x64_sys_execve+0x0    [FTRACE]
        ffffffff91345650  k  __x64_sys_execve+0x0    [DISABLED][FTRACE]
      
      4. Kill execsnoop, when __disable_kprobe() calls disarm_kprobe() for the
         disabled kprobe and hits the WARN_ONCE() in __disarm_kprobe_ftrace().
      
        # fg
        /usr/share/bcc/tools/execsnoop
        ^C
      
      Actually, WARN_ONCE() is fired twice, and __unregister_kprobe_top() misses
      some cleanups and leaves the aggregated kprobe in the hash table.  Then,
      __unregister_trace_kprobe() initialises tk->rp.kp.list and creates an
      infinite loop like this.
      
        aggregated kprobe.list -> kprobe.list -.
                                           ^    |
                                           '.__.'
      
      In this situation, these commands fall into the infinite loop and result
      in RCU stall or soft lockup.
      
        cat /sys/kernel/debug/kprobes/list : show_kprobe_addr() enters into the
                                             infinite loop with RCU.
      
        /usr/share/bcc/tools/execsnoop : warn_kprobe_rereg() holds kprobe_mutex,
                                         and __get_valid_kprobe() is stuck in
      				   the loop.
      
      To avoid the issue, make sure we don't call disarm_kprobe() for disabled
      kprobes.
      
      [0]
      Failed to disarm kprobe-ftrace at __x64_sys_execve+0x0/0x40 (error -2)
      WARNING: CPU: 6 PID: 2460 at kernel/kprobes.c:1130 __disarm_kprobe_ftrace.isra.19 (kernel/kprobes.c:1129)
      Modules linked in: ena
      CPU: 6 PID: 2460 Comm: execsnoop Not tainted 5.19.0+ #28
      Hardware name: Amazon EC2 c5.2xlarge/, BIOS 1.0 10/16/2017
      RIP: 0010:__disarm_kprobe_ftrace.isra.19 (kernel/kprobes.c:1129)
      Code: 24 8b 02 eb c1 80 3d c4 83 f2 01 00 75 d4 48 8b 75 00 89 c2 48 c7 c7 90 fa 0f 92 89 04 24 c6 05 ab 83 01 e8 e4 94 f0 ff <0f> 0b 8b 04 24 eb b1 89 c6 48 c7 c7 60 fa 0f 92 89 04 24 e8 cc 94
      RSP: 0018:ffff9e6ec154bd98 EFLAGS: 00010282
      RAX: 0000000000000000 RBX: ffffffff930f7b00 RCX: 0000000000000001
      RDX: 0000000080000001 RSI: ffffffff921461c5 RDI: 00000000ffffffff
      RBP: ffff89c504286da8 R08: 0000000000000000 R09: c0000000fffeffff
      R10: 0000000000000000 R11: ffff9e6ec154bc28 R12: ffff89c502394e40
      R13: ffff89c502394c00 R14: ffff9e6ec154bc00 R15: 0000000000000000
      FS:  00007fe800398740(0000) GS:ffff89c812d80000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 000000c00057f010 CR3: 0000000103b54006 CR4: 00000000007706e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
      PKRU: 55555554
      Call Trace:
      <TASK>
       __disable_kprobe (kernel/kprobes.c:1716)
       disable_kprobe (kernel/kprobes.c:2392)
       __disable_trace_kprobe (kernel/trace/trace_kprobe.c:340)
       disable_trace_kprobe (kernel/trace/trace_kprobe.c:429)
       perf_trace_event_unreg.isra.2 (./include/linux/tracepoint.h:93 kernel/trace/trace_event_perf.c:168)
       perf_kprobe_destroy (kernel/trace/trace_event_perf.c:295)
       _free_event (kernel/events/core.c:4971)
       perf_event_release_kernel (kernel/events/core.c:5176)
       perf_release (kernel/events/core.c:5186)
       __fput (fs/file_table.c:321)
       task_work_run (./include/linux/sched.h:2056 (discriminator 1) kernel/task_work.c:179 (discriminator 1))
       exit_to_user_mode_prepare (./include/linux/resume_user_mode.h:49 kernel/entry/common.c:169 kernel/entry/common.c:201)
       syscall_exit_to_user_mode (./arch/x86/include/asm/jump_label.h:55 ./arch/x86/include/asm/nospec-branch.h:384 ./arch/x86/include/asm/entry-common.h:94 kernel/entry/common.c:133 kernel/entry/common.c:296)
       do_syscall_64 (arch/x86/entry/common.c:87)
       entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
      RIP: 0033:0x7fe7ff210654
      Code: 15 79 89 20 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb be 0f 1f 00 8b 05 9a cd 20 00 48 63 ff 85 c0 75 11 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 3a f3 c3 48 83 ec 18 48 89 7c 24 08 e8 34 fc
      RSP: 002b:00007ffdbd1d3538 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
      RAX: 0000000000000000 RBX: 0000000000000008 RCX: 00007fe7ff210654
      RDX: 0000000000000000 RSI: 0000000000002401 RDI: 0000000000000008
      RBP: 0000000000000000 R08: 94ae31d6fda838a4 R0900007fe8001c9d30
      R10: 00007ffdbd1d34b0 R11: 0000000000000246 R12: 00007ffdbd1d3600
      R13: 0000000000000000 R14: fffffffffffffffc R15: 00007ffdbd1d3560
      </TASK>
      
      Link: https://lkml.kernel.org/r/20220813020509.90805-1-kuniyu@amazon.com
      Fixes: 69d54b91
      
       ("kprobes: makes kprobes/enabled works correctly for optimized kprobes.")
      Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
      Reported-by: default avatarAyushman Dutta <ayudutta@amazon.com>
      Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
      Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Wang Nan <wangnan0@huawei.com>
      Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
      Cc: Kuniyuki Iwashima <kuni1840@gmail.com>
      Cc: Ayushman Dutta <ayudutta@amazon.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      19cd6307
    • Jann Horn's avatar
      mm/rmap: Fix anon_vma->degree ambiguity leading to double-reuse · c24ca0f1
      Jann Horn authored
      commit 2555283e upstream.
      
      anon_vma->degree tracks the combined number of child anon_vmas and VMAs
      that use the anon_vma as their ->anon_vma.
      
      anon_vma_clone() then assumes that for any anon_vma attached to
      src->anon_vma_chain other than src->anon_vma, it is impossible for it to
      be a leaf node of the VMA tree, meaning that for such VMAs ->degree is
      elevated by 1 because of a child anon_vma, meaning that if ->degree
      equals 1 there are no VMAs that use the anon_vma as their ->anon_vma.
      
      This assumption is wrong because the ->degree optimization leads to leaf
      nodes being abandoned on anon_vma_clone() - an existing anon_vma is
      reused and no new parent-child relationship is created.  So it is
      possible to reuse an anon_vma for one VMA while it is still tied to
      another VMA.
      
      This is an issue because is_mergeable_anon_vma() and its callers assume
      that if two VMAs have the same ->anon_vma, the list of anon_vmas
      attached to the VMAs is guaranteed to be the same.  When this assumption
      is violated, vma_merge() can merge pages into a VMA that is not attached
      to the corresponding anon_vma, leading to dangling page->mapping
      pointers that will be dereferenced during rmap walks.
      
      Fix it by separately tracking the number of child anon_vmas and the
      number of VMAs using the anon_vma as their ->anon_vma.
      
      Fixes: 7a3ef208
      
       ("mm: prevent endless growth of anon_vma hierarchy")
      Cc: stable@kernel.org
      Acked-by: default avatarMichal Hocko <mhocko@suse.com>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarJann Horn <jannh@google.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      [manually fixed up different indentation in stable]
      Signed-off-by: default avatarJann Horn <jannh@google.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c24ca0f1
    • Geert Uytterhoeven's avatar
      netfilter: conntrack: NF_CONNTRACK_PROCFS should no longer default to y · e7a5ead5
      Geert Uytterhoeven authored
      [ Upstream commit aa5762c3 ]
      
      NF_CONNTRACK_PROCFS was marked obsolete in commit 54b07dca
      
      
      ("netfilter: provide config option to disable ancient procfs parts") in
      v3.3.
      
      Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
      Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
      Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
      e7a5ead5
    • Juergen Gross's avatar
      s390/hypfs: avoid error message under KVM · 4a06817c
      Juergen Gross authored
      [ Upstream commit 7b6670b0
      
       ]
      
      When booting under KVM the following error messages are issued:
      
      hypfs.7f5705: The hardware system does not support hypfs
      hypfs.7a79f0: Initialization of hypfs failed with rc=-61
      
      Demote the severity of first message from "error" to "info" and issue
      the second message only in other error cases.
      
      Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
      Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
      Acked-by: default avatarChristian Borntraeger <borntraeger@linux.ibm.com>
      Link: https://lore.kernel.org/r/20220620094534.18967-1-jgross@suse.com
      
      
      [arch/s390/hypfs/hypfs_diag.c changed description]
      Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
      Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
      4a06817c
    • Hsin-Yi Wang's avatar
      arm64: map FDT as RW for early_init_dt_scan() · 3e930a2d
      Hsin-Yi Wang authored
      commit e112b032
      
       upstream.
      
      Currently in arm64, FDT is mapped to RO before it's passed to
      early_init_dt_scan(). However, there might be some codes
      (eg. commit "fdt: add support for rng-seed") that need to modify FDT
      during init. Map FDT to RO after early fixups are done.
      
      Signed-off-by: default avatarHsin-Yi Wang <hsinyi@chromium.org>
      Reviewed-by: default avatarStephen Boyd <swboyd@chromium.org>
      Reviewed-by: default avatarMike Rapoport <rppt@linux.ibm.com>
      Signed-off-by: default avatarWill Deacon <will@kernel.org>
      [mkbestas: fixed trivial conflicts for 4.9 backport]
      Signed-off-by: default avatarMichael Bestas <mkbestas@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3e930a2d
    • Yang Jihong's avatar
      ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead · 8569b4ad
      Yang Jihong authored
      commit c3b0f72e upstream.
      
      ftrace_startup does not remove ops from ftrace_ops_list when
      ftrace_startup_enable fails:
      
      register_ftrace_function
        ftrace_startup
          __register_ftrace_function
            ...
            add_ftrace_ops(&ftrace_ops_list, ops)
            ...
          ...
          ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1
          ...
        return 0 // ops is in the ftrace_ops_list.
      
      When ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything:
      unregister_ftrace_function
        ftrace_shutdown
          if (unlikely(ftrace_disabled))
                  return -ENODEV;  // return here, __unregister_ftrace_function is not executed,
                                   // as a result, ops is still in the ftrace_ops_list
          __unregister_ftrace_function
          ...
      
      If ops is dynamically allocated, it will be free later, in this case,
      is_ftrace_trampoline accesses NULL pointer:
      
      is_ftrace_trampoline
        ftrace_ops_trampoline
          do_for_each_ftrace_op(op, ftrace_ops_list) // OOPS! op may be NULL!
      
      Syzkaller reports as follows:
      [ 1203.506103] BUG: kernel NULL pointer dereference, address: 000000000000010b
      [ 1203.508039] #PF: supervisor read access in kernel mode
      [ 1203.508798] #PF: error_code(0x0000) - not-present page
      [ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0
      [ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI
      [ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Tainted: G    B   W         5.10.0 #8
      [ 1203.512324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
      [ 1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0
      [ 1203.514644] Code: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00
      [ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246
      [ 1203.520092] RAX: 0000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866
      [ 1203.521469] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000000010b
      [ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07
      [ 1203.523550] R10: fffffbfff1be3160 R11: 0000000000000001 R12: 0000000000478399
      [ 1203.524596] R13: 0000000000000000 R14: ffff888145088000 R15: 0000000000000008
      [ 1203.525634] FS:  00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000
      [ 1203.526801] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [ 1203.527626] CR2: 000000000000010b CR3: 0000000170e1e001 CR4: 00000000003706e0
      [ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      [ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
      
      Therefore, when ftrace_startup_enable fails, we need to rollback registration
      process and remove ops from ftrace_ops_list.
      
      Link: https://lkml.kernel.org/r/20220818032659.56209-1-yangjihong1@huawei.com
      
      
      
      Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarYang Jihong <yangjihong1@huawei.com>
      Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8569b4ad