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Commit d7f58d5f authored by David Miller's avatar David Miller Committed by Greg Kroah-Hartman
Browse files

sparc64: Make corrupted user stacks more debuggable. 



[ Upstream commit 5b4fc3882a649c9411dd0dcad2ddb78e911d340e ]

Right now if we get a corrupted user stack frame we do a
do_exit(SIGILL) which is not helpful.

If under a debugger, this behavior causes the inferior process to
exit.  So the register and other state cannot be examined at the time
of the event.

Instead, conditionally log a rate limited kernel log message and then
force a SIGSEGV.

With bits and ideas borrowed (as usual) from powerpc.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9b5bc99b

arch/sparc/include/asm/switch_to_64.h

+2 −1
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ do { save_and_clear_fpu(); \ 
} while(0)



void synchronize_user_stack(void);

void fault_in_user_windows(void);

struct pt_regs;

void fault_in_user_windows(struct pt_regs *);



#endif /* __SPARC64_SWITCH_TO_64_H */

arch/sparc/kernel/process_64.c

+19 −6
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/sysrq.h>

#include <linux/nmi.h>

#include <linux/context_tracking.h>

#include <linux/signal.h>



#include <linux/uaccess.h>

#include <asm/page.h>
@@ -521,7 +522,12 @@ static void stack_unaligned(unsigned long sp) 
	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0, current);

}



void fault_in_user_windows(void)

static const char uwfault32[] = KERN_INFO \

	"%s[%d]: bad register window fault: SP %08lx (orig_sp %08lx) TPC %08lx O7 %08lx\n";

static const char uwfault64[] = KERN_INFO \

	"%s[%d]: bad register window fault: SP %016lx (orig_sp %016lx) TPC %08lx O7 %016lx\n";



void fault_in_user_windows(struct pt_regs *regs)

{

	struct thread_info *t = current_thread_info();

	unsigned long window;
@@ -534,9 +540,9 @@ void fault_in_user_windows(void) 
		do {

			struct reg_window *rwin = &t->reg_window[window];

			int winsize = sizeof(struct reg_window);

			unsigned long sp;

			unsigned long sp, orig_sp;



			sp = t->rwbuf_stkptrs[window];

			orig_sp = sp = t->rwbuf_stkptrs[window];



			if (test_thread_64bit_stack(sp))

				sp += STACK_BIAS;
@@ -547,8 +553,16 @@ void fault_in_user_windows(void) 
				stack_unaligned(sp);



			if (unlikely(copy_to_user((char __user *)sp,

						  rwin, winsize)))

						  rwin, winsize))) {

				if (show_unhandled_signals)

					printk_ratelimited(is_compat_task() ?

							   uwfault32 : uwfault64,

							   current->comm, current->pid,

							   sp, orig_sp,

							   regs->tpc,

							   regs->u_regs[UREG_I7]);

				goto barf;

			}

		} while (window--);

	}

	set_thread_wsaved(0);
@@ -556,8 +570,7 @@ void fault_in_user_windows(void) 


barf:

	set_thread_wsaved(window + 1);

	user_exit();

	do_exit(SIGILL);

	force_sig(SIGSEGV, current);

}



asmlinkage long sparc_do_fork(unsigned long clone_flags,

arch/sparc/kernel/rtrap_64.S

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ __handle_preemption: 
		 wrpr			%g0, RTRAP_PSTATE_IRQOFF, %pstate



__handle_user_windows:

		add			%sp, PTREGS_OFF, %o0

		call			fault_in_user_windows

661:		 wrpr			%g0, RTRAP_PSTATE, %pstate

		/* If userspace is using ADI, it could potentially pass

arch/sparc/kernel/signal32.c

+10 −2
Original line number Diff line number Diff line
@@ -371,7 +371,11 @@ static int setup_frame32(struct ksignal *ksig, struct pt_regs *regs, 
		get_sigframe(ksig, regs, sigframe_size);

	

	if (invalid_frame_pointer(sf, sigframe_size)) {

		do_exit(SIGILL);

		if (show_unhandled_signals)

			pr_info("%s[%d] bad frame in setup_frame32: %08lx TPC %08lx O7 %08lx\n",

				current->comm, current->pid, (unsigned long)sf,

				regs->tpc, regs->u_regs[UREG_I7]);

		force_sigsegv(ksig->sig, current);

		return -EINVAL;

	}
@@ -501,7 +505,11 @@ static int setup_rt_frame32(struct ksignal *ksig, struct pt_regs *regs, 
		get_sigframe(ksig, regs, sigframe_size);

	

	if (invalid_frame_pointer(sf, sigframe_size)) {

		do_exit(SIGILL);

		if (show_unhandled_signals)

			pr_info("%s[%d] bad frame in setup_rt_frame32: %08lx TPC %08lx O7 %08lx\n",

				current->comm, current->pid, (unsigned long)sf,

				regs->tpc, regs->u_regs[UREG_I7]);

		force_sigsegv(ksig->sig, current);

		return -EINVAL;

	}

arch/sparc/kernel/signal_64.c

+5 −1
Original line number Diff line number Diff line
@@ -370,7 +370,11 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 
		get_sigframe(ksig, regs, sf_size);



	if (invalid_frame_pointer (sf)) {

		do_exit(SIGILL);	/* won't return, actually */

		if (show_unhandled_signals)

			pr_info("%s[%d] bad frame in setup_rt_frame: %016lx TPC %016lx O7 %016lx\n",

				current->comm, current->pid, (unsigned long)sf,

				regs->tpc, regs->u_regs[UREG_I7]);

		force_sigsegv(ksig->sig, current);

		return -EINVAL;

	}