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SubjectRe: 2.6.{26.2,27-rc} oops on virtualbox
Was looking at the code stream, and noticed this:

Code: c0 0f 84 0b 01 00 00 b8 d0 bf 41 c0 c7 05 6c c0 41 c0 ff ff ff ff
e8 7f 82 21 00 e8 1a 03 02 00 8b 45 b0 50 9d 0f 1f 84 00 00 00 <00> 00
8b 45 bc 83 c4 60 5b 5e 5f 5d c3 66 90 a1 6c c0 41 c0 e8

Code: c0 0f 84 0b 01 00 00 b8 d0 bf 41 c0 c7 05 6c c0 41 c0 ff ff ff ff
e8 7f 82 21 00 e8 1a 03 02 00 8b 45 b0 50 9d 0f 1f 84 00 00 00 <00> 00
8b 45 bc 83 c4 60 5b 5e 5f 5d c3 66 90 a1 6c c0 41 c0 e8

The EIP is in the *MIDDLE* of a NOPL instruction:

C012FC46 C00F84 ror byte [edi],0x84
C012FC49 0B01 or eax,[ecx]
C012FC4B 0000 add [eax],al
C012FC4D B8D0BF41C0 mov eax,0xc041bfd0
C012FC52 C7056CC041C0FFFF mov dword [dword 0xc041c06c],0xffffffff
-FFFF
C012FC5C E87F822100 call dword 0xc0347ee0
C012FC61 E81A030200 call dword 0xc014ff80
C012FC66 8B45B0 mov eax,[ebp-0x50]
C012FC69 50 push eax
C012FC6A 9D popfd
C012FC6B 0F1F840000000000 nop dword [eax+eax+0x0]
C012FC73 8B45BC mov eax,[ebp-0x44]
C012FC76 83C460 add esp,byte +0x60
C012FC79 5B pop ebx
C012FC7A 5E pop esi
C012FC7B 5F pop edi
C012FC7C 5D pop ebp
C012FC7D C3 ret
C012FC7E 6690 xchg ax,ax
C012FC80 A16CC041C0 mov eax,[0xc041c06c]

There are two possibilities: VirtualBox mis-executes (not merely traps,
which is what tip:master looks for) the NOPL instruction, or something
is jumping into the middle of the sequence that is then replaced by the
NOPL.

So, Luiz: the DEBUG_INFO version of vmlinux would be helpful. It would
also help to know the exact version of VirtualBox you're running, what
source you got it from, and what your host system looks like.

-hpa


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