[linux-security] Modified floppies can crash Linux

KiloByte (kilobyte@mimuw.edu.pl)
Mon, 23 Mar 1998 16:39:45 +0100

Hi!
While playing with file allocation tables, I noticed that if a FAT volume
(eg. a floppy) with looped allocation chain is being read under Linux, the
system stops responding and cannot be recovered to a working state without
a hardware rebooting.
This bug is not-so-useful for performing Denial-Of-Service attacks (if an
evildoer managed to put a floppy into your computer, why won't he just
press the power switch?), although he can leave a modified floppy on your
desk. It is sufficient to just ls that floppy.

Sample exploit is at http://rainbow.mimuw.edu.pl/~ab171958/FAT.html#Linux

I tested this exploit on kernel versions 2.0.30, 2.0.31 and 2.0.32, it
always works.

/-----------------------\ Hiroshima'45
| kilobyte@mimuw.edu.pl | Chernobyl'86
\-----------------------/ Windows'95
http://rainbow.mimuw.edu.pl/~ab171958/

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