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Re: [PATCH] be paranoid about closed stdin/stdout/stderr
- Date: Wed, 27 Aug 2008 10:20:23 +0200
- From: Paolo Bonzini <bonzini@xxxxxxx>
- Subject: Re: [PATCH] be paranoid about closed stdin/stdout/stderr
>> Busybox. But it runs setuid, as Steven pointed out.
>
> I straced tee (it was the only tool I found that opens files for writing
> without also opening some for reading). If one of 0,1,2 is closed, it
> *does* dup() the fd that it is going to write.
To be precise, it does a blind "dup2 (fd, 3)" and goes on with file
descriptor 3.
open("foo", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 0
fcntl64(0, F_DUPFD, 3) = 3
close(0) = 0
Paolo
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