1. 28 Feb, 2016 2 commits
  2. 12 Apr, 2015 1 commit
  3. 13 Feb, 2015 1 commit
    • Andy Lutomirski's avatar
      all arches, signal: move restart_block to struct task_struct · f56141e3
      Andy Lutomirski authored
      
      
      If an attacker can cause a controlled kernel stack overflow, overwriting
      the restart block is a very juicy exploit target.  This is because the
      restart_block is held in the same memory allocation as the kernel stack.
      
      Moving the restart block to struct task_struct prevents this exploit by
      making the restart_block harder to locate.
      
      Note that there are other fields in thread_info that are also easy
      targets, at least on some architectures.
      
      It's also a decent simplification, since the restart code is more or less
      identical on all architectures.
      
      [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: David Miller <davem@davemloft.net>
      Acked-by: default avatarRichard Weinberger <richard@nod.at>
      Cc: Richard Henderson <rth@twiddle.net>
      Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
      Cc: Matt Turner <mattst88@gmail.com>
      Cc: Vineet Gupta <vgupta@synopsys.com>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
      Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
      Cc: Steven Miao <realmz6@gmail.com>
      Cc: Mark Salter <msalter@redhat.com>
      Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
      Cc: Mikael Starvik <starvik@axis.com>
      Cc: Jesper Nilsson <jesper.nilsson@axis.com>
      Cc: David Howells <dhowells@redhat.com>
      Cc: Richard Kuo <rkuo@codeaurora.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Geert Uytterhoeven <geert@linux-m68k.org>
      Cc: Michal Simek <monstr@monstr.eu>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Jonas Bonn <jonas@southpole.se>
      Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
      Cc: Helge Deller <deller@gmx.de>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
      Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Chen Liqin <liqin.linux@gmail.com>
      Cc: Lennox Wu <lennox.wu@gmail.com>
      Cc: Chris Metcalf <cmetcalf@ezchip.com>
      Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
      Cc: Chris Zankel <chris@zankel.net>
      Cc: Max Filippov <jcmvbkbc@gmail.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Guenter Roeck <linux@roeck-us.net>
      Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f56141e3
  4. 08 Sep, 2014 2 commits
  5. 10 Jul, 2014 1 commit
  6. 22 May, 2014 1 commit
  7. 12 May, 2014 1 commit
  8. 08 May, 2014 1 commit
    • Ard Biesheuvel's avatar
      arm64: defer reloading a task's FPSIMD state to userland resume · 005f78cd
      Ard Biesheuvel authored
      
      
      If a task gets scheduled out and back in again and nothing has touched
      its FPSIMD state in the mean time, there is really no reason to reload
      it from memory. Similarly, repeated calls to kernel_neon_begin() and
      kernel_neon_end() will preserve and restore the FPSIMD state every time.
      
      This patch defers the FPSIMD state restore to the last possible moment,
      i.e., right before the task returns to userland. If a task does not return to
      userland at all (for any reason), the existing FPSIMD state is preserved
      and may be reused by the owning task if it gets scheduled in again on the
      same CPU.
      
      This patch adds two more functions to abstract away from straight FPSIMD
      register file saves and restores:
      - fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded
      - fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      005f78cd
  9. 13 Nov, 2013 1 commit
  10. 26 Jul, 2013 1 commit
  11. 17 Sep, 2012 1 commit
  12. 21 Nov, 2011 1 commit
  13. 17 Mar, 2011 1 commit
  14. 02 Oct, 2010 1 commit
  15. 14 May, 2010 1 commit
  16. 15 Feb, 2010 1 commit
  17. 02 Sep, 2009 1 commit
  18. 15 Aug, 2009 1 commit
    • Mikael Pettersson's avatar
      ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait · 36984265
      Mikael Pettersson authored
      
      
      This patch adds support for TIF_RESTORE_SIGMASK to ARM's
      signal handling, which allows to hook up the pselect6, ppoll,
      and epoll_pwait syscalls on ARM.
      
      Tested here with eabi userspace and a test program with a
      deliberate race between a child's exit and the parent's
      sigprocmask/select sequence. Using sys_pselect6() instead
      of sigprocmask/select reliably prevents the race.
      
      The other arch's support for TIF_RESTORE_SIGMASK has evolved
      over time:
      
      In 2.6.16:
      - add TIF_RESTORE_SIGMASK which parallels TIF_SIGPENDING
      - test both when checking for pending signal [changed later]
      - reimplement sys_sigsuspend() to use current->saved_sigmask,
        TIF_RESTORE_SIGMASK [changed later], and -ERESTARTNOHAND;
        ditto for sys_rt_sigsuspend(), but drop private code and
        use common code via __ARCH_WANT_SYS_RT_SIGSUSPEND;
      - there are now no "extra" calls to do_signal() so its oldset
        parameter is always &current->blocked so need not be passed,
        also its return value is changed to void
      - change handle_signal() to return 0/-errno
      - change do_signal() to honor TIF_RESTORE_SIGMASK:
        + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
          is set
        + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
        + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
          clear it and restore the sigmask
      - hook up sys_pselect6() and sys_ppoll()
      
      In 2.6.19:
      - hook up sys_epoll_pwait()
      
      In 2.6.26:
      - allow archs to override how TIF_RESTORE_SIGMASK is implemented;
        default set_restore_sigmask() sets both TIF_RESTORE_SIGMASK and
        TIF_SIGPENDING; archs need now just test TIF_SIGPENDING again
        when checking for pending signal work; some archs now implement
        TIF_RESTORE_SIGMASK as a secondary/non-atomic thread flag bit
      - call set_restore_sigmask() in sys_sigsuspend() instead of setting
        TIF_RESTORE_SIGMASK
      
      In 2.6.29-rc:
      - kill sys_pselect7() which no arch wanted
      
      So for 2.6.31-rc6/ARM this patch does the following:
      - Add TIF_RESTORE_SIGMASK. Use the generic set_restore_sigmask()
        which sets both TIF_SIGPENDING and TIF_RESTORE_SIGMASK, so
        TIF_RESTORE_SIGMASK need not claim one of the scarce low thread
        flags, and existing TIF_SIGPENDING and _TIF_WORK_MASK tests need
        not be extended for TIF_RESTORE_SIGMASK.
      - sys_sigsuspend() is reimplemented to use current->saved_sigmask
        and set_restore_sigmask(), making it identical to most other archs
      - The private code for sys_rt_sigsuspend() is removed, instead
        generic code supplies it via __ARCH_WANT_SYS_RT_SIGSUSPEND.
      - sys_sigsuspend() and sys_rt_sigsuspend() no longer need a pt_regs
        parameter, so their assembly code wrappers are removed.
      - handle_signal() is changed to return 0 on success or -errno.
      - The oldset parameter to do_signal() is now redundant and removed,
        and the return value is now also redundant and changed to void.
      - do_signal() is changed to honor TIF_RESTORE_SIGMASK:
        + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
          is set
        + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
        + if no signal was delivered and TIF_RESTORE_SIGMASK is set then
          clear it and restore the sigmask
      - Hook up sys_pselect6, sys_ppoll, and sys_epoll_pwait.
      Signed-off-by: default avatarMikael Pettersson <mikpe@it.uu.se>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      36984265
  19. 10 Jul, 2009 1 commit
  20. 12 Feb, 2009 2 commits
  21. 06 Sep, 2008 1 commit
  22. 02 Aug, 2008 1 commit
  23. 25 Jul, 2008 1 commit
  24. 18 Apr, 2008 1 commit
  25. 31 Jul, 2007 1 commit
  26. 20 Jul, 2007 1 commit
  27. 06 May, 2007 1 commit
  28. 13 Dec, 2006 1 commit
    • Rafael J. Wysocki's avatar
      [PATCH] PM: Fix SMP races in the freezer · 8a102eed
      Rafael J. Wysocki authored
      
      
      Currently, to tell a task that it should go to the refrigerator, we set the
      PF_FREEZE flag for it and send a fake signal to it.  Unfortunately there
      are two SMP-related problems with this approach.  First, a task running on
      another CPU may be updating its flags while the freezer attempts to set
      PF_FREEZE for it and this may leave the task's flags in an inconsistent
      state.  Second, there is a potential race between freeze_process() and
      refrigerator() in which freeze_process() running on one CPU is reading a
      task's PF_FREEZE flag while refrigerator() running on another CPU has just
      set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it.  If
      the refrigerator wins the race, freeze_process() will state that PF_FREEZE
      hasn't been set for the task and will set it unnecessarily, so the task
      will go to the refrigerator once again after it's been thawed.
      
      To solve first of these problems we need to stop using PF_FREEZE to tell
      tasks that they should go to the refrigerator.  Instead, we can introduce a
      special TIF_*** flag and use it for this purpose, since it is allowed to
      change the other tasks' TIF_*** flags and there are special calls for it.
      
      To avoid the freeze_process()-refrigerator() race we can make
      freeze_process() to always check the task's PF_FROZEN flag after it's read
      its "freeze" flag.  We should also make sure that refrigerator() will
      always reset the task's "freeze" flag after it's set PF_FROZEN for it.
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Acked-by: default avatarPavel Machek <pavel@ucw.cz>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: David Howells <dhowells@redhat.com>
      Cc: Andi Kleen <ak@muc.de>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8a102eed
  29. 30 Nov, 2006 1 commit
    • Paul Gortmaker's avatar
      [ARM] 3911/2: Simplify alloc_thread_info on ARM · 12221442
      Paul Gortmaker authored
      
      
      Remove ARM local cache of 4 struct thread_info.
      Can cause oops under certain circumstances.
      
      Russell indicated the original optimization was
      required on older kernels to avoid thread starvation
      on memory fragmentation, but may no longer be
      required.  I've updated the patch to 19rc4 and
      ensured no <config.h> dain-bramage slipped in this
      time (sorry about that).
      
      Original description follows:
      
      I was given some test results which pointed to an
      Oops in alloc_thread_info (happened 2x), and after
      looking at the code, I see that ARM has its own
      local cache of 4 struct thread_info. There wasn't
      any clear (to me) synchronization between the
      alloc_thread_info and the free_thread_info.
      
      I looked over the other arch, and they all simply
      allocate them on an as needed basis, so I simplified
      the ARM to do the same, based on the other arch
      (e.g. PPC) and the folks doing the testing have
      indicated that this fixed the oops.
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      12221442
  30. 01 Jul, 2006 1 commit
  31. 30 Jun, 2006 1 commit
  32. 28 Jun, 2006 1 commit
  33. 12 Mar, 2006 1 commit
  34. 12 Jan, 2006 2 commits
  35. 16 Nov, 2005 1 commit
  36. 23 Jun, 2005 1 commit
    • Jesper Juhl's avatar
      [PATCH] streamline preempt_count type across archs · dcd497f9
      Jesper Juhl authored
      
      
      The preempt_count member of struct thread_info is currently either defined
      as int, unsigned int or __s32 depending on arch.  This patch makes the type
      of preempt_count an int on all archs.
      
      Having preempt_count be an unsigned type prevents the catching of
      preempt_count < 0 bugs, and using int on some archs and __s32 on others is
      not exactely "neat" - much nicer when it's just int all over.
      
      A previous version of this patch was already ACK'ed by Robert Love, and the
      only change in this version of the patch compared to the one he ACK'ed is
      that this one also makes sure the preempt_count member is consistently
      commented.
      Signed-off-by: default avatarJesper Juhl <juhl-lkml@dif.dk>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      dcd497f9