1. 27 Jan, 2015 37 commits
  2. 16 Jan, 2015 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.14.29 · a2ab9187
      Greg Kroah-Hartman authored
      a2ab9187
    • Linus Torvalds's avatar
      mm: Don't count the stack guard page towards RLIMIT_STACK · 1bec714a
      Linus Torvalds authored
      commit 690eac53 upstream.
      
      Commit fee7e49d ("mm: propagate error from stack expansion even for
      guard page") made sure that we return the error properly for stack
      growth conditions.  It also theorized that counting the guard page
      towards the stack limit might break something, but also said "Let's see
      if anybody notices".
      
      Somebody did notice.  Apparently android-x86 sets the stack limit very
      close to the limit indeed, and including the guard page in the rlimit
      check causes the android 'zygote' process problems.
      
      So this adds the (fairly trivial) code to make the stack rlimit check be
      against the actual real stack size, rather than the size of the vma that
      includes the guard page.
      Reported-and-tested-by: default avatarChih-Wei Huang <cwhuang@android-x86.org>
      Cc: Jay Foad <jay.foad@gmail.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1bec714a
    • Linus Torvalds's avatar
      mm: propagate error from stack expansion even for guard page · 11e4f3bf
      Linus Torvalds authored
      commit fee7e49d upstream.
      
      Jay Foad reports that the address sanitizer test (asan) sometimes gets
      confused by a stack pointer that ends up being outside the stack vma
      that is reported by /proc/maps.
      
      This happens due to an interaction between RLIMIT_STACK and the guard
      page: when we do the guard page check, we ignore the potential error
      from the stack expansion, which effectively results in a missing guard
      page, since the expected stack expansion won't have been done.
      
      And since /proc/maps explicitly ignores the guard page (commit
      d7824370: "mm: fix up some user-visible effects of the stack guard
      page"), the stack pointer ends up being outside the reported stack area.
      
      This is the minimal patch: it just propagates the error.  It also
      effectively makes the guard page part of the stack limit, which in turn
      measn that the actual real stack is one page less than the stack limit.
      
      Let's see if anybody notices.  We could teach acct_stack_growth() to
      allow an extra page for a grow-up/grow-down stack in the rlimit test,
      but I don't want to add more complexity if it isn't needed.
      Reported-and-tested-by: default avatarJay Foad <jay.foad@gmail.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      11e4f3bf