lkml.org 
[lkml]   [2018]   [May]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: WARNING in arch_uprobe_analyze_insn
    On 05/14, syzbot wrote:
    >
    > Hello,
    >
    > syzbot found the following crash on:
    >
    > HEAD commit: 66e1c94db3cd Merge branch 'x86-pti-for-linus' of git://git..
    > git tree: upstream
    > console output: https://syzkaller.appspot.com/x/log.txt?x=11817107800000
    > kernel config: https://syzkaller.appspot.com/x/.config?x=fcce42b221691ff9
    > dashboard link: https://syzkaller.appspot.com/bug?extid=30d675e3ca03c1c351e7
    > compiler: gcc (GCC) 8.0.1 20180413 (experimental)
    > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=143d5417800000
    > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11178e97800000

    doesn't work for me...

    I guess syscall(__NR_perf_event_open) should trigger perf_uprobe_init() but
    the hard-coded attr.type doesn't match perf_uprobe->type on my machine...


    Nevermind, it seems that the code is indeed wrong, uprobe_init_insn() does

    insn_init(insn, auprobe->insn, sizeof(auprobe->insn), x86_64);
    /* has the side-effect of processing the entire instruction */
    insn_get_length(insn);
    if (WARN_ON_ONCE(!insn_complete(insn)))
    return -ENOEXEC;

    Masami, could your help?

    What if insn can't be decoded, say, because it is not valid? Can't
    insn_complete() return F in this case?

    I think it can... Say, insn_get_immediate() doesn't set immediate.got in
    err_out path.

    Unfortunately, insn_get_length() returns void, and I do not see any
    insn-was-decoded-correctly helper. Perhaps we should simply remove
    this WARN_ON() ?

    Alternatively, If am right we can move this check down after the "good_insns"
    checks, but this doesn't look very clean to me.


    > IMPORTANT: if you fix the bug, please add the following tag to the commit:
    > Reported-by: syzbot+30d675e3ca03c1c351e7@syzkaller.appspotmail.com
    >
    > random: sshd: uninitialized urandom read (32 bytes read)
    > random: sshd: uninitialized urandom read (32 bytes read)
    > random: sshd: uninitialized urandom read (32 bytes read)
    > random: sshd: uninitialized urandom read (32 bytes read)
    > random: sshd: uninitialized urandom read (32 bytes read)
    > WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296 insn_complete
    > arch/x86/include/asm/insn.h:147 [inline]
    > WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296 uprobe_init_insn
    > arch/x86/kernel/uprobes.c:296 [inline]
    > WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296
    > arch_uprobe_analyze_insn+0x13d/0x15f0 arch/x86/kernel/uprobes.c:861
    > Kernel panic - not syncing: panic_on_warn set ...
    >
    > CPU: 0 PID: 4511 Comm: syz-executor347 Not tainted 4.17.0-rc4+ #46
    > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
    > Google 01/01/2011
    > Call Trace:
    > __dump_stack lib/dump_stack.c:77 [inline]
    > dump_stack+0x1b9/0x294 lib/dump_stack.c:113
    > panic+0x22f/0x4de kernel/panic.c:184
    > __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
    > report_bug+0x252/0x2d0 lib/bug.c:186
    > fixup_bug arch/x86/kernel/traps.c:178 [inline]
    > do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
    > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
    > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
    > RIP: 0010:insn_complete arch/x86/include/asm/insn.h:147 [inline]
    > RIP: 0010:uprobe_init_insn arch/x86/kernel/uprobes.c:296 [inline]
    > RIP: 0010:arch_uprobe_analyze_insn+0x13d/0x15f0
    > arch/x86/kernel/uprobes.c:861
    > RSP: 0018:ffff8801cf277510 EFLAGS: 00010246
    > RAX: 0000000000000000 RBX: ffff8801cf277560 RCX: ffffffff876ccf2a
    > RDX: 0000000000000004 RSI: ffffffff876ce6ab RDI: ffff8801cf27759c
    > RBP: ffff8801cf277628 R08: ffff8801d8c0a5c0 R09: ffff8801cf277560
    > R10: ffff8801d7ad81d0 R11: ffff8801cf2775af R12: 0000000000000000
    > R13: dffffc0000000000 R14: ffff8801d7ad8080 R15: ffff8801cf277600
    > prepare_uprobe kernel/events/uprobes.c:610 [inline]
    > install_breakpoint.isra.21+0x710/0x830 kernel/events/uprobes.c:657
    > uprobe_mmap+0x6a0/0xcf0 kernel/events/uprobes.c:1089
    > mmap_region+0x5c8/0x1870 mm/mmap.c:1807
    > do_mmap+0xde2/0x1360 mm/mmap.c:1535
    > do_mmap_pgoff include/linux/mm.h:2237 [inline]
    > vm_mmap_pgoff+0x1fb/0x2a0 mm/util.c:357
    > ksys_mmap_pgoff+0x4c9/0x640 mm/mmap.c:1585
    > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
    > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
    > __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
    > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
    > entry_SYSCALL_64_after_hwframe+0x49/0xbe
    > RIP: 0033:0x43ff29
    > RSP: 002b:00007ffc922a4898 EFLAGS: 00000212 ORIG_RAX: 0000000000000009
    > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ff29
    > RDX: 0000000000000000 RSI: 0000000000002000 RDI: 000000002000c000
    > RBP: 00000000006ca018 R08: 0000000000000003 R09: 0000000000000000
    > R10: 0000000000000012 R11: 0000000000000212 R12: 0000000000401850
    > R13: 00000000004018e0 R14: 0000000000000000 R15: 0000000000000000
    > Dumping ftrace buffer:
    > (ftrace buffer empty)
    > Kernel Offset: disabled
    > Rebooting in 86400 seconds..
    >
    >
    > ---
    > This bug is generated by a bot. It may contain errors.
    > See https://goo.gl/tpsmEJ for more information about syzbot.
    > syzbot engineers can be reached at syzkaller@googlegroups.com.
    >
    > syzbot will keep track of this bug report. See:
    > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
    > syzbot.
    > syzbot can test patches for this bug, for details see:
    > https://goo.gl/tpsmEJ#testing-patches

    \
     
     \ /
      Last update: 2018-05-15 15:36    [W:3.363 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site