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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f56141e3e2
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>
77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
#ifndef _ASM_M68K_THREAD_INFO_H
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#define _ASM_M68K_THREAD_INFO_H
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#include <asm/types.h>
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#include <asm/page.h>
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#include <asm/segment.h>
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/*
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* On machines with 4k pages we default to an 8k thread size, though we
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* allow a 4k with config option. Any other machine page size then
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* the thread size must match the page size (which is 8k and larger here).
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*/
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#if PAGE_SHIFT < 13
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#ifdef CONFIG_4KSTACKS
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#define THREAD_SIZE 4096
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#else
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#define THREAD_SIZE 8192
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#endif
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#else
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#define THREAD_SIZE PAGE_SIZE
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#endif
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#define THREAD_SIZE_ORDER ((THREAD_SIZE / PAGE_SIZE) - 1)
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#ifndef __ASSEMBLY__
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struct thread_info {
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struct task_struct *task; /* main task structure */
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unsigned long flags;
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struct exec_domain *exec_domain; /* execution domain */
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mm_segment_t addr_limit; /* thread address space */
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int preempt_count; /* 0 => preemptable, <0 => BUG */
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__u32 cpu; /* should always be 0 on m68k */
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unsigned long tp_value; /* thread pointer */
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};
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#endif /* __ASSEMBLY__ */
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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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.addr_limit = KERNEL_DS, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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}
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#define init_stack (init_thread_union.stack)
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#ifndef __ASSEMBLY__
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/* how to get the thread information struct from C */
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static inline struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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__asm__(
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"move.l %%sp, %0 \n\t"
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"and.l %1, %0"
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: "=&d"(ti)
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: "di" (~(THREAD_SIZE-1))
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);
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return ti;
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}
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#endif
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#define init_thread_info (init_thread_union.thread_info)
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/* entry.S relies on these definitions!
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* bits 0-7 are tested at every exception exit
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* bits 8-15 are also tested at syscall exit
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*/
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#define TIF_NOTIFY_RESUME 5 /* callback before returning to user */
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#define TIF_SIGPENDING 6 /* signal pending */
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#define TIF_NEED_RESCHED 7 /* rescheduling necessary */
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#define TIF_DELAYED_TRACE 14 /* single step a syscall */
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#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
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#define TIF_MEMDIE 16 /* is terminating due to OOM killer */
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#define TIF_RESTORE_SIGMASK 18 /* restore signal mask in do_signal */
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#endif /* _ASM_M68K_THREAD_INFO_H */
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