[Bug 239980] Allowing maximum value to option "-l" in combination with option "-G", "-g", "-s" and "-f" makes system (host and guest) in freeze/hang condition by eating full CPU and RAM resources

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Mon Aug 19 23:33:10 UTC 2019


https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239980

            Bug ID: 239980
           Summary: Allowing maximum value to option "-l" in combination
                    with option "-G", "-g", "-s" and "-f" makes system
                    (host and guest) in freeze/hang condition by eating
                    full CPU and RAM resources
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: bin
          Assignee: bugs at FreeBSD.org
          Reporter: neerajpal09 at gmail.com

There is a issue after running the command given below on my FreeBSD virtual
machine, it suddenly start eating my all CPU and RAM resources and I have
observed the hangs/freezing behaviour on my guest machine which also impacts
the host machine in 10-30 seconds.

After observing such behaviour I am sure that after leaving it for some minutes
or hours. It could lead to DOS.

* ping -s 56 -G 4294967297 -g 4294967292 -l 429496729 -f localhost

or

* ping -s 56 -G maximum_allowed_value -g minimum_allowed_value -l 429496729 -f
localhost


I think it should not allowed to preload (-l) this much value, especially with
option "-f".

top(1) info given below (only in 13 seconds this much usage):

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
 2456 root          1  93    0    11M  2604K CPU2     2   0:13  99.51% ping
  723 root          1  94    0    21M  9848K CPU3     3   1:21  91.98% sshd

I am connected via ssh and have observed that everytime when I run the above
mentioned ping command then the usage of sshd daemon also increases suddenly
(as given in the above top(1) info).

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