1. 22 Mar, 2016 36 commits
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  3. 14 Mar, 2016 1 commit
  4. 10 Mar, 2016 1 commit
    • Willy Tarreau's avatar
      pipe: limit the per-user amount of pages allocated in pipes · ac0d50a3
      Willy Tarreau authored
      commit 759c0114 upstream.
      
      On no-so-small systems, it is possible for a single process to cause an
      OOM condition by filling large pipes with data that are never read. A
      typical process filling 4000 pipes with 1 MB of data will use 4 GB of
      memory. On small systems it may be tricky to set the pipe max size to
      prevent this from happening.
      
      This patch makes it possible to enforce a per-user soft limit above
      which new pipes will be limited to a single page, effectively limiting
      them to 4 kB each, as well as a hard limit above which no new pipes may
      be created for this user. This has the effect of protecting the system
      against memory abuse without hurting other users, and still allowing
      pipes to work correctly though with less data at once.
      
      The limit are controlled by two new sysctls : pipe-user-pages-soft, and
      pipe-user-pages-hard. Both may be disabled by setting them to zero. The
      default soft limit allows the default number of FDs per process (1024)
      to create pipes of the default size (64kB), thus reaching a limit of 64MB
      before starting to create only smaller pipes. With 256 processes limited
      to 1024 FDs each, this results in 1024*64kB + (256*1024 - 1024) * 4kB =
      1084 MB of memory allocated for a user. The hard limit is disabled by
      default to avoid breaking existing applications that make intensive use
      of pipes (eg: for splicing).
      
      Reported-by: socketpair@gmail.com
      Reported-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Mitigates: CVE-2013-4312 (Linux 2.0+)
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      ac0d50a3