Eric Lee / smarc-fsl-linux-kernel

28 Sep, 2014

2 commits

  • 72cf90124   lzo: check for length overrun in variable length encoding. ... Browse Code »

    This fix ensures that we never meet an integer overflow while adding
    255 while parsing a variable length encoding. It works differently from
    commit 206a81c ("lzo: properly check for overruns") because instead of
    ensuring that we don't overrun the input, which is tricky to guarantee
    due to many assumptions in the code, it simply checks that the cumulated
    number of 255 read cannot overflow by bounding this number.

    The MAX_255_COUNT is the maximum number of times we can add 255 to a base
    count without overflowing an integer. The multiply will overflow when
    multiplying 255 by more than MAXINT/255. The sum will overflow earlier
    depending on the base count. Since the base count is taken from a u8
    and a few bits, it is safe to assume that it will always be lower than
    or equal to 2*255, thus we can always prevent any overflow by accepting
    two less 255 steps.

    This patch also reduces the CPU overhead and actually increases performance
    by 1.1% compared to the initial code, while the previous fix costs 3.1%
    (measured on x86_64).

    The fix needs to be backported to all currently supported stable kernels.

    Reported-by: Willem Pinckaers
    Cc: "Don A. Bailey"
    Cc: stable
    Signed-off-by: Willy Tarreau
    Signed-off-by: Greg Kroah-Hartman

    Willy Tarreau
     
  • af958a38a   Revert "lzo: properly check for overruns" ... Browse Code »

    This reverts commit 206a81c ("lzo: properly check for overruns").

    As analysed by Willem Pinckaers, this fix is still incomplete on
    certain rare corner cases, and it is easier to restart from the
    original code.

    Reported-by: Willem Pinckaers
    Cc: "Don A. Bailey"
    Cc: stable
    Signed-off-by: Willy Tarreau
    Signed-off-by: Greg Kroah-Hartman

    Willy Tarreau
     

24 Jun, 2014

1 commit

  • 206a81c18   lzo: properly check for overruns ... Browse Code »

    The lzo decompressor can, if given some really crazy data, possibly
    overrun some variable types. Modify the checking logic to properly
    detect overruns before they happen.

    Reported-by: "Don A. Bailey"
    Tested-by: "Don A. Bailey"
    Cc: stable
    Signed-off-by: Greg Kroah-Hartman

    Greg Kroah-Hartman
     

21 Feb, 2013

2 commits