On Fri, Mar 25, 2011 at 12:00, Akinobu Mita <akinobu.mita@xxxxxxxxx> wrote:
find_next bitops on m68k (find_next_zero_bit, find_next_bit, and
find_next_bit_le) may cause out of bounds memory access
when the bitmap size in bits % 32 != 0 and offset (the bitnumber
to start searching at) is very close to the bitmap size.
For example,
   unsigned long bitmap[2] = { 0, 0 };
   find_next_bit(bitmap, 63, 62);
1. find_next_bit() tries to find any set bits in bitmap[1],
 but no bits set.
2. Then find_first_bit(bimap + 2, -1)
3. Unfortunately find_fist_bit() takes unsigned int as the size argument.
4. find_first_bit will access bitmap[2~] until it find any set bits.
This switches find_next bitops to use generic implementation of
find bitops to fix the problem.
Andreas, do you think it's worth keeping (and fixing) the m68k "optimized"
versions?
Gr{oetje,eeting}s,
            Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
             Â Â -- Linus Torvalds
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