linux-kernel - Re: [PATCH v5 5/8] powerpc/watchpoint: Fix exception handling for CONFIG_HAVE_HW

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1e706137-3de9-a713-5a86-48fbc5e6f740@linux.ibm.com>
Date:   Tue, 25 Aug 2020 16:37:57 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        christophe.leroy@....fr
Cc:     mpe@...erman.id.au, mikey@...ling.org, paulus@...ba.org,
        naveen.n.rao@...ux.vnet.ibm.com, pedromfc@...ux.ibm.com,
        rogealve@...ux.ibm.com, jniethe5@...il.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v5 5/8] powerpc/watchpoint: Fix exception handling for
 CONFIG_HAVE_HW_BREAKPOINT=N

Hi Christophe,

>> diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
>> index 57a0ab822334..866597b407bc 100644
>> --- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
>> +++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
>> @@ -286,11 +286,16 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
>>       }
>>       return ret;
>>   #else /* CONFIG_HAVE_HW_BREAKPOINT */
>> +    if (child->thread.hw_brk[data - 1].flags & HW_BRK_FLAG_DISABLED)
> 
> I think child->thread.hw_brk[data - 1].flags & HW_BRK_FLAG_DISABLED should go around additionnal ()

Not sure I follow.

> 
>> +        goto del;
>> +
>>       if (child->thread.hw_brk[data - 1].address == 0)
>>           return -ENOENT;
> 
> What about replacing the above if by:
>      if (!(child->thread.hw_brk[data - 1].flags) & HW_BRK_FLAG_DISABLED) &&
>          child->thread.hw_brk[data - 1].address == 0)
>          return -ENOENT;
okay.. that's more compact.

But more importantly, what I wanted to know is whether CONFIG_HAVE_HW_BREAKPOINT
is set or not in production/distro builds for 8xx. Because I see it's not set in
8xx defconfigs.

Thanks,
Ravi