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From: Borislav Petkov <bp@alien8.de>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzbot <syzbot+9cf5373b0e15476f39a2@syzkaller.appspotmail.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	the arch/x86 maintainers <x86@kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: invalid opcode in map_vdso
Date: Wed, 23 Sep 2020 12:30:08 +0200	[thread overview]
Message-ID: <20200923103008.GE28545@zn.tnic> (raw)
In-Reply-To: <CACT4Y+YGFtPCi3a-ByZGs1kCFfJOYv_AbkxOG=K_D4xh0r4okA@mail.gmail.com>

On Wed, Sep 23, 2020 at 11:19:40AM +0200, Dmitry Vyukov wrote:
> +clang-built-linux
> Looks like another one with kernel code overwrite in clang build.

Uuh, that's a nice and refreshing one - the pattern is not zeroes this
time

Code: 16 48 89 ef 48 8b 34 24 31 c9 e8 88 7c a7 00 eb 7a 4c 8b 74 24 28 43 80 3c 3e 00 48 8b 5c 24 08 74 08 4c 89 ef e8 4d 77 70 70 <07> 20 05 00 00 49 03 6d 00 48 89 e8 48 c1 e8 03 42 80 3c 38 00 74
All code
========
   0:   16                      (bad)  
   1:   48 89 ef                mov    %rbp,%rdi
   4:   48 8b 34 24             mov    (%rsp),%rsi
   8:   31 c9                   xor    %ecx,%ecx
   a:   e8 88 7c a7 00          callq  0xa77c97
   f:   eb 7a                   jmp    0x8b
  11:   4c 8b 74 24 28          mov    0x28(%rsp),%r14
  16:   43 80 3c 3e 00          cmpb   $0x0,(%r14,%r15,1)
  1b:   48 8b 5c 24 08          mov    0x8(%rsp),%rbx
  20:   74 08                   je     0x2a
  22:   4c 89 ef                mov    %r13,%rdi
  25:   e8 4d 77 70 70          callq  0x70707777
  2a:*  07                      (bad)           <-- trapping instruction
  2b:   20 05 00 00 49 03       and    %al,0x3490000(%rip)        # 0x3490031
  31:   6d                      insl   (%dx),%es:(%rdi)
  32:   00 48 89                add    %cl,-0x77(%rax)
  35:   e8 48 c1 e8 03          callq  0x3e8c182
  3a:   42 80 3c 38 00          cmpb   $0x0,(%rax,%r15,1)
  3f:   74                      .byte 0x74

Code starting with the faulting instruction
===========================================
   0:   07                      (bad)  
   1:   20 05 00 00 49 03       and    %al,0x3490000(%rip)        # 0x3490007
   7:   6d                      insl   (%dx),%es:(%rdi)
   8:   00 48 89                add    %cl,-0x77(%rax)
   b:   e8 48 c1 e8 03          callq  0x3e8c158
  10:   42 80 3c 38 00          cmpb   $0x0,(%rax,%r15,1)
  15:   74                      .byte 0x74

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2020-09-23 10:30 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23  9:18 invalid opcode in map_vdso syzbot
2020-09-23  9:19 ` Dmitry Vyukov
2020-09-23 10:30   ` Borislav Petkov [this message]
2020-09-25 12:16     ` Dmitry Vyukov

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