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Date: Thu, 16 Jan 2014 09:34:26 +0800
From: orc <orc@...server.ru>
To: musl@...ts.openwall.com
Subject: Re: install.sh is wrong with libc.so
Rich Felker <dalias@...ifal.cx> пишет:
>On Wed, Jan 15, 2014 at 08:48:18PM +0800, orc wrote:
>> Szabolcs Nagy <nsz@...t70.net> пишет:
>> >* orc <orc@...server.ru> [2014-01-15 16:42:08 +0800]:
>> >> umask 077
>> >> cat < lib/libc.so > /lib/libc.so.tmp.pid # /lib/libc.so.tmp.pid is
>> >created with mode 600
>> >> mv -f /lib/libc.so.tmp.pid /lib/libc.so
>> >> chmod 755 /lib/libc.so # failed with "Permission denied"
>> >>
>> >> After that the system is unusable and requires external
>assistance.
>> >
>> >this is why you should have chmod statically linked
>
>In fairness, my having chmod statically linked is why I didn't catch
>this bug...
>
>> I agree with that. For historical reasons it's not. But I expected
>> musl will continue to use standard install program.
>
>Unfortunately the "standard" (historical) install program is even more
>dangerous; it truncates and overwrites the file in-place rather than
>atomically renaming the new version over top of the old. This can
>crash any programs currently running with the old version and could
>even result in runaway random code execution. This was the motivation
>for replacing it with musl's install.sh.
>
>Regardless of that, I agree the current order (chmod after mv) is a
>serious bug in atomicity of the install, and I apologize for the
>breakage you experienced. I'm glad it got reported so we can fix it
>before 1.0 though.
>
Thanks for detailed explanation and quick fix!
>Rich
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