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  1. 05 6月, 2009 1 次提交
    • S
      drivers/char/mem.c: avoid OOM lockup during large reads from /dev/zero · 730c586a
      由 Salman Qazi 提交于 
      While running 20 parallel instances of dd as follows:

  #!/bin/bash
  for i in `seq 1 20`; do
           dd if=/dev/zero of=/export/hda3/dd_$i bs=1073741824 count=1 &
  done
  wait

on a 16G machine, we noticed that rather than just killing the processes,
the entire kernel went down.  Stracing dd reveals that it first does an
mmap2, which makes 1GB worth of zero page mappings.  Then it performs a
read on those pages from /dev/zero, and finally it performs a write.

The machine died during the reads.  Looking at the code, it was noticed
that /dev/zero's read operation had been changed by
557ed1fa ("remove ZERO_PAGE") from giving
zero page mappings to actually zeroing the page.

The zeroing of the pages causes physical pages to be allocated to the
process.  But, when the process exhausts all the memory that it can, the
kernel cannot kill it, as it is still in the kernel mode allocating more
memory.  Consequently, the kernel eventually crashes.

To fix this, I propose that when a fatal signal is pending during
/dev/zero read operation, we simply return and let the user process die.
Signed-off-by: NSalman Qazi <sqazi@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ Modified error return and comment trivially.  - Linus]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      730c586a
  3. 04 6月, 2009 8 次提交
  5. 03 6月, 2009 2 次提交
  7. 02 6月, 2009 2 次提交
    • N
      e1000: add missing length check to e1000 receive routine · ea30e119
      由 Neil Horman 提交于 
      	Patch to fix bad length checking in e1000.  E1000 by default does two
things:

1) Spans rx descriptors for packets that don't fit into 1 skb on recieve
2) Strips the crc from a frame by subtracting 4 bytes from the length prior to
doing an skb_put

Since the e1000 driver isn't written to support receiving packets that span
multiple rx buffers, it checks the End of Packet bit of every frame, and
discards it if its not set.  This places us in a situation where, if we have a
spanning packet, the first part is discarded, but the second part is not (since
it is the end of packet, and it passes the EOP bit test).  If the second part of
the frame is small (4 bytes or less), we subtract 4 from it to remove its crc,
underflow the length, and wind up in skb_over_panic, when we try to skb_put a
huge number of bytes into the skb.  This amounts to a remote DOS attack through
careful selection of frame size in relation to interface MTU.  The fix for this
is already in the e1000e driver, as well as the e1000 sourceforge driver, but no
one ever pushed it to e1000.  This is lifted straight from e1000e, and prevents
small frames from causing the underflow described above
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Tested-by: NAndy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ea30e119
    • E
      forcedeth: add phy_power_down parameter, leave phy powered up by default (v2) · 5a9a8e32
      由 Ed Swierk 提交于 
      Add a phy_power_down parameter to forcedeth: set to 1 to power down the
phy and disable the link when an interface goes down; set to 0 to always
leave the phy powered up.

The phy power state persists across reboots; Windows, some BIOSes, and
older versions of Linux don't bother to power up the phy again, forcing
users to remove all power to get the interface working (see
http://bugzilla.kernel.org/show_bug.cgi?id=13072).  Leaving the phy
powered on is the safest default behavior.  Users accustomed to seeing
the link state reflect the interface state and/or wanting to minimize
power consumption can set phy_power_down=1 if compatibility with other
OSes is not an issue.
Signed-off-by: NEd Swierk <eswierk@aristanetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5a9a8e32
  9. 01 6月, 2009 2 次提交
  11. 31 5月, 2009 1 次提交
  13. 30 5月, 2009 8 次提交
  15. 29 5月, 2009 16 次提交