
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: Andy 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 <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: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
3.4 KiB
C
106 lines
3.4 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_THREAD_INFO_H
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#define __ASM_AVR32_THREAD_INFO_H
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#include <asm/page.h>
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#define THREAD_SIZE_ORDER 1
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#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
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#ifndef __ASSEMBLY__
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#include <asm/types.h>
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struct task_struct;
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struct exec_domain;
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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unsigned long flags; /* low level flags */
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__u32 cpu;
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__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
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__u32 rar_saved; /* return address... */
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__u32 rsr_saved; /* ...and status register
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saved by debug handler
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when setting up
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trampoline */
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__u8 supervisor_stack[0];
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};
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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/*
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* Get the thread information struct from C.
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* We do the usual trick and use the lower end of the stack for this
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*/
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static inline struct thread_info *current_thread_info(void)
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{
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unsigned long addr = ~(THREAD_SIZE - 1);
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asm("and %0, sp" : "=r"(addr) : "0"(addr));
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return (struct thread_info *)addr;
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}
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#define get_thread_info(ti) get_task_struct((ti)->task)
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#define put_thread_info(ti) put_task_struct((ti)->task)
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#endif /* !__ASSEMBLY__ */
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/*
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* Thread information flags
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* - these are process state flags that various assembly files may need to access
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* - pending work-to-be-done flags are in LSW
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* - other flags in MSW
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_BREAKPOINT 4 /* enter monitor mode on return */
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#define TIF_SINGLE_STEP 5 /* single step in progress */
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#define TIF_MEMDIE 6 /* is terminating due to OOM killer */
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#define TIF_RESTORE_SIGMASK 7 /* restore signal mask in do_signal */
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#define TIF_CPU_GOING_TO_SLEEP 8 /* CPU is entering sleep 0 mode */
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#define TIF_NOTIFY_RESUME 9 /* callback before returning to user */
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#define TIF_DEBUG 30 /* debugging enabled */
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#define TIF_USERSPACE 31 /* true if FS sets userspace */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_BREAKPOINT (1 << TIF_BREAKPOINT)
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#define _TIF_SINGLE_STEP (1 << TIF_SINGLE_STEP)
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#define _TIF_MEMDIE (1 << TIF_MEMDIE)
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#define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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/* Note: The masks below must never span more than 16 bits! */
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/* work to do on interrupt/exception return */
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#define _TIF_WORK_MASK \
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(_TIF_SIGPENDING \
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| _TIF_NOTIFY_RESUME \
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| _TIF_NEED_RESCHED \
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| _TIF_BREAKPOINT)
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/* work to do on any return to userspace */
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#define _TIF_ALLWORK_MASK (_TIF_WORK_MASK | _TIF_SYSCALL_TRACE)
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/* work to do on return from debug mode */
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#define _TIF_DBGWORK_MASK (_TIF_WORK_MASK & ~_TIF_BREAKPOINT)
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#endif /* __ASM_AVR32_THREAD_INFO_H */
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