1. 28 9月, 2014 2 次提交
    • W
      lzo: check for length overrun in variable length encoding. · 72cf9012
      Willy Tarreau 提交于
      This fix ensures that we never meet an integer overflow while adding
      255 while parsing a variable length encoding. It works differently from
      commit 206a81c1 ("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: NWillem Pinckaers <willem@lekkertech.net>
      Cc: "Don A. Bailey" <donb@securitymouse.com>
      Cc: stable <stable@vger.kernel.org>
      Signed-off-by: NWilly Tarreau <w@1wt.eu>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      72cf9012
    • W
      Revert "lzo: properly check for overruns" · af958a38
      Willy Tarreau 提交于
      This reverts commit 206a81c1 ("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: NWillem Pinckaers <willem@lekkertech.net>
      Cc: "Don A. Bailey" <donb@securitymouse.com>
      Cc: stable <stable@vger.kernel.org>
      Signed-off-by: NWilly Tarreau <w@1wt.eu>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      af958a38
  2. 24 6月, 2014 1 次提交
  3. 21 2月, 2013 2 次提交
  4. 12 1月, 2010 1 次提交
    • A
      lib: add support for LZO-compressed kernels · 7dd65feb
      Albin Tonnerre 提交于
      This patch series adds generic support for creating and extracting
      LZO-compressed kernel images, as well as support for using such images on
      the x86 and ARM architectures, and support for creating and using
      LZO-compressed initrd and initramfs images.
      
      Russell King said:
      
      : Testing on a Cortex A9 model:
      : - lzo decompressor is 65% of the time gzip takes to decompress a kernel
      : - lzo kernel is 9% larger than a gzip kernel
      :
      : which I'm happy to say confirms your figures when comparing the two.
      :
      : However, when comparing your new gzip code to the old gzip code:
      : - new is 99% of the size of the old code
      : - new takes 42% of the time to decompress than the old code
      :
      : What this means is that for a proper comparison, the results get even better:
      : - lzo is 7.5% larger than the old gzip'd kernel image
      : - lzo takes 28% of the time that the old gzip code took
      :
      : So the expense seems definitely worth the effort.  The only reason I
      : can think of ever using gzip would be if you needed the additional
      : compression (eg, because you have limited flash to store the image.)
      :
      : I would argue that the default for ARM should therefore be LZO.
      
      This patch:
      
      The lzo compressor is worse than gzip at compression, but faster at
      extraction.  Here are some figures for an ARM board I'm working on:
      
      Uncompressed size: 3.24Mo
      gzip  1.61Mo 0.72s
      lzo   1.75Mo 0.48s
      
      So for a compression ratio that is still relatively close to gzip, it's
      much faster to extract, at least in that case.
      
      This part contains:
       - Makefile routine to support lzo compression
       - Fixes to the existing lzo compressor so that it can be used in
         compressed kernels
       - wrapper around the existing lzo1x_decompress, as it only extracts one
         block at a time, while we need to extract a whole file here
       - config dialog for kernel compression
      
      [akpm@linux-foundation.org: coding-style fixes]
      [akpm@linux-foundation.org: cleanup]
      Signed-off-by: NAlbin Tonnerre <albin.tonnerre@free-electrons.com>
      Tested-by: NWu Zhangjin <wuzhangjin@gmail.com>
      Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Tested-by: NRussell King <rmk@arm.linux.org.uk>
      Acked-by: NRussell King <rmk@arm.linux.org.uk>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7dd65feb
  5. 26 7月, 2008 1 次提交
  6. 11 4月, 2008 1 次提交
  7. 01 8月, 2007 1 次提交
  8. 11 7月, 2007 1 次提交
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