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authorAndy Lutomirski <luto@amacapital.net>2015-02-12 18:01:14 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 21:54:12 -0500
commitf56141e3e2d9aabf7e6b89680ab572c2cdbb2a24 (patch)
tree481e3d99bc1121ce75d505d340153b9d158e60c5 /arch/m68k
parentedc924e023ae2022fc29f1246e115c610c9abf38 (diff)
all arches, signal: move restart_block to struct task_struct
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>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/include/asm/thread_info.h4
-rw-r--r--arch/m68k/kernel/signal.c4
2 files changed, 2 insertions, 6 deletions
diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h
index 21a4784ca5a1..c54256e69e64 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -31,7 +31,6 @@ struct thread_info {
31 int preempt_count; /* 0 => preemptable, <0 => BUG */ 31 int preempt_count; /* 0 => preemptable, <0 => BUG */
32 __u32 cpu; /* should always be 0 on m68k */ 32 __u32 cpu; /* should always be 0 on m68k */
33 unsigned long tp_value; /* thread pointer */ 33 unsigned long tp_value; /* thread pointer */
34 struct restart_block restart_block;
35}; 34};
36#endif /* __ASSEMBLY__ */ 35#endif /* __ASSEMBLY__ */
37 36
@@ -41,9 +40,6 @@ struct thread_info {
41 .exec_domain = &default_exec_domain, \ 40 .exec_domain = &default_exec_domain, \
42 .addr_limit = KERNEL_DS, \ 41 .addr_limit = KERNEL_DS, \
43 .preempt_count = INIT_PREEMPT_COUNT, \ 42 .preempt_count = INIT_PREEMPT_COUNT, \
44 .restart_block = { \
45 .fn = do_no_restart_syscall, \
46 }, \
47} 43}
48 44
49#define init_stack (init_thread_union.stack) 45#define init_stack (init_thread_union.stack)
diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index 967a8b7e1527..d7179281e74a 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -655,7 +655,7 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *usc, void __u
655 int err = 0; 655 int err = 0;
656 656
657 /* Always make any pending restarted system calls return -EINTR */ 657 /* Always make any pending restarted system calls return -EINTR */
658 current_thread_info()->restart_block.fn = do_no_restart_syscall; 658 current->restart_block.fn = do_no_restart_syscall;
659 659
660 /* get previous context */ 660 /* get previous context */
661 if (copy_from_user(&context, usc, sizeof(context))) 661 if (copy_from_user(&context, usc, sizeof(context)))
@@ -693,7 +693,7 @@ rt_restore_ucontext(struct pt_regs *regs, struct switch_stack *sw,
693 int err; 693 int err;
694 694
695 /* Always make any pending restarted system calls return -EINTR */ 695 /* Always make any pending restarted system calls return -EINTR */
696 current_thread_info()->restart_block.fn = do_no_restart_syscall; 696 current->restart_block.fn = do_no_restart_syscall;
697 697
698 err = __get_user(temp, &uc->uc_mcontext.version); 698 err = __get_user(temp, &uc->uc_mcontext.version);
699 if (temp != MCONTEXT_VERSION) 699 if (temp != MCONTEXT_VERSION)