Re: [uml-devel] trinity commit 23dc478aba breaks syscall "mremap" at a 32 bit user mode linux

[Richard Weinberger <richard@nod.at>]

Am 01.05.2014 23:34, schrieb Toralf Förster:
> On 05/01/2014 10:57 PM, Richard Weinberger wrote:
>> Toralf,
>>
>> Yeah, this is because trinity destroys the UML stub code.
>> Please test the attached patch, it should fix the root cause of the problem.
>>
>> Thanks,
>> //richard
>>
> 
> If I do just apply fix2.patch onto latest git tree  v3.15-rc3-113-gba6728f then I do get after a while :
> 
>  * Starting sshd ...                                                                                                  [ ok ]
>  * Starting local
> net.core.warnings = 0                                                                                                 [ ok ]
> Kernel panic - not syncing: do_syscall_stub : PTRACE_SETREGS failed, errno = 3
> 
> CPU: 0 PID: 1728 Comm: trinity-c0 Not tainted 3.15.0-rc3-00113-gba6728f-dirty #5
> Stack:
> BUG: soft lockup - CPU#0 stuck for 22s! [trinity-c0:1728]
> 
> EIP: c500:[<47c6cf00>] CPU: 0 Not tainted EFLAGS: 476af700
>     Not tainted
> EAX: 47cfc500 EBX: 0a024d00 ECX: 086c75fc EDX: 080fff88
> ESI: 0839f4bc EDI: 47cfc500 EBP: 0839f4bc DS: c500 ES: cd62
> EXT4-fs (ubda): error count: 1
> EXT4-fs (ubda): initial error at 1398962134: ext4_mb_generate_buddy:756
> EXT4-fs (ubda): last error at 1398962134: ext4_mb_generate_buddy:756

Hmm, there is another bug hidden.
/me looks.

> 
> which is a big improvement because before it crashes immediately after few seconds.
> 
> After applying both fixes the test case runs w/o a crash till now.

It should work without removing the panics().
Otherwise an attacker could do nasty things.

Thanks,
//richard