• 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: Richard Weinberger's 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
signal.c 16.7 KB