Messages in this thread | | | Date | Fri, 17 Sep 2004 06:54:07 -0700 | From | William Lee Irwin III <> | Subject | Re: truncate shows non zero data beyond the end of the inode with MAP_SHARED |
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On Fri, Sep 17, 2004 at 03:49:18PM +0200, Helge Hafting wrote: > I am not talking about someone accidentally stumbling onto > something. I was worried about someone deliberately > trying to exploit this - such people look at data above i_size > _because they can_, hoping to find something interesting there. > Something they cannot get at normally. > I am assuming that the "garbage" between i_size and the > page boundary is stuff left over from whatever that > memory page was used for earlier? If so, it could be > 4095 bytes out of the 4096 that was used to cache some > other file earlier. Possibly someone else's confidential file. > Or a piece of some network package that was processed a while ago.
This issue is only of userspace data leaking into pagecache at file offsets just beyond where the end of a file formerly was (no further than the former last page, but beyond the former end of the file), not kernel data leaking to userspace.
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