Commit f56141e3 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Linus Torvalds
Browse files

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: 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>
parent edc924e0
......@@ -27,8 +27,6 @@ struct thread_info {
int bpt_nsaved;
unsigned long bpt_addr[2]; /* breakpoint handling */
unsigned int bpt_insn[2];
struct restart_block restart_block;
};
/*
......@@ -40,9 +38,6 @@ struct thread_info {
.exec_domain = &default_exec_domain, \
.addr_limit = KERNEL_DS, \
.preempt_count = INIT_PREEMPT_COUNT, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -150,7 +150,7 @@ restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
struct switch_stack *sw = (struct switch_stack *)regs - 1;
long i, err = __get_user(regs->pc, &sc->sc_pc);
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
sw->r26 = (unsigned long) ret_from_sys_call;
......
......@@ -46,7 +46,6 @@ struct thread_info {
struct exec_domain *exec_domain;/* execution domain */
__u32 cpu; /* current CPU */
unsigned long thr_ptr; /* TLS ptr */
struct restart_block restart_block;
};
/*
......@@ -62,9 +61,6 @@ struct thread_info {
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -104,7 +104,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
struct pt_regs *regs = current_pt_regs();
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/* Since we stacked the signal on a word boundary,
* then 'sp' should be word aligned here. If it's
......
......@@ -68,7 +68,6 @@ struct thread_info {
#ifdef CONFIG_ARM_THUMBEE
unsigned long thumbee_state; /* ThumbEE Handler Base register */
#endif
struct restart_block restart_block;
};
#define INIT_THREAD_INFO(tsk) \
......@@ -81,9 +80,6 @@ struct thread_info {
.cpu_domain = domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
domain_val(DOMAIN_IO, DOMAIN_CLIENT), \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -191,7 +191,7 @@ asmlinkage int sys_sigreturn(struct pt_regs *regs)
struct sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
......@@ -221,7 +221,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
struct rt_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
......
......@@ -48,7 +48,6 @@ struct thread_info {
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
struct restart_block restart_block;
int preempt_count; /* 0 => preemptable, <0 => bug */
int cpu; /* cpu */
};
......@@ -60,9 +59,6 @@ struct thread_info {
.flags = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -131,7 +131,7 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
struct rt_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 128-bit boundary, then 'sp' should
......
......@@ -347,7 +347,7 @@ asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
struct compat_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
......@@ -381,7 +381,7 @@ asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
struct compat_rt_sigframe __user *frame;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
......
......@@ -30,7 +30,6 @@ struct thread_info {
saved by debug handler
when setting up
trampoline */
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
......@@ -41,9 +40,6 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.restart_block = { \
.fn = do_no_restart_syscall \
} \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -18,7 +18,6 @@ void foo(void)
OFFSET(TI_preempt_count, thread_info, preempt_count);
OFFSET(TI_rar_saved, thread_info, rar_saved);
OFFSET(TI_rsr_saved, thread_info, rsr_saved);
OFFSET(TI_restart_block, thread_info, restart_block);
BLANK();
OFFSET(TSK_active_mm, task_struct, active_mm);
BLANK();
......
......@@ -69,7 +69,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
frame = (struct rt_sigframe __user *)regs->sp;
pr_debug("SIG return: frame = %p\n", frame);
......
......@@ -42,7 +42,6 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct restart_block restart_block;
#ifndef CONFIG_SMP
struct l1_scratch_task_info l1_task_info;
#endif
......@@ -58,9 +57,6 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
#define init_stack (init_thread_union.stack)
......
......@@ -44,7 +44,7 @@ rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *p
int err = 0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
#define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
......
......@@ -45,7 +45,6 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 = preemptable, <0 = BUG */
mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
};
/*
......@@ -61,9 +60,6 @@ struct thread_info {
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -68,7 +68,7 @@ asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a dword boundary,
......
......@@ -67,7 +67,7 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
unsigned long old_usp;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/* restore the regs from &sc->regs (same as sc, since regs is first)
* (sc is already checked for VERIFY_READ since the sigframe was
......
......@@ -59,7 +59,7 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
unsigned long old_usp;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
current->restart_block.fn = do_no_restart_syscall;
/*
* Restore the registers from &sc->regs. sc is already checked
......
......@@ -38,7 +38,6 @@ struct thread_info {
0-0xBFFFFFFF for user-thead
0-0xFFFFFFFF for kernel-thread
*/
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
......@@ -56,9 +55,6 @@ struct thread_info {
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
......@@ -41,7 +41,6 @@ struct thread_info {
* 0-0xBFFFFFFF for user-thead
* 0-0xFFFFFFFF for kernel-thread
*/
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
......@@ -65,9 +64,6 @@ struct thread_info {
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
}
#define init_thread_info (init_thread_union.thread_info)
......
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