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Re: [PATCH -tip 2/2] Pass mm->flags as a coredump parameter for consistency
- From: Hidehiro Kawai <hidehiro dot kawai dot ez at hitachi dot com>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>, Roland McGrath <roland at redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, Oleg Nesterov <oleg at redhat dot com>
- Date: Thu, 19 Nov 2009 21:57:37 +0900
- Subject: Re: [PATCH -tip 2/2] Pass mm->flags as a coredump parameter for consistency
- References: <20091117235305.30900.43344.stgit@dhcp-100-2-132.bos.redhat.com> <20091117235401.30900.70697.stgit@dhcp-100-2-132.bos.redhat.com>
Hi Hiramatsu-san,
Masami Hiramatsu wrote:
>> Pass mm->flags as a coredump parameter for consistency.
>>
>> ---
>> 1787 if (mm->core_state || !get_dumpable(mm)) { <- (1)
>> 1788 up_write(&mm->mmap_sem);
>> 1789 put_cred(cred);
>> 1790 goto fail;
>> 1791 }
>> 1792
>> [...]
>> 1798 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ <-(2)
>> 1799 flag = O_EXCL; /* Stop rewrite attacks */
>> 1800 cred->fsuid = 0; /* Dump root private */
>> 1801 }
>> ---
>>
>> Since dumpable bits are not protected by lock, there is a
>> chance to change these bits between (1) and (2).
Yes, a race condition can be caused by prctl from another thread.
And your patch is fine with me. Thanks!
Reviewed-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
--
Hidehiro Kawai
Hitachi, Systems Development Laboratory
Linux Technology Center