Commit 119cd59f authored by Al Viro's avatar Al Viro
Browse files

x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit) 



Straightforward, except for save_altstack_ex() stuck in those.
Replace that thing with an analogue that would use unsafe_put_user()
instead of put_user_ex() (called compat_save_altstack()) and be done
with that.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 57d563c8

arch/x86/kernel/signal.c

+48 −43
Original line number Diff line number Diff line
@@ -365,28 +365,27 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 


	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);



	if (!access_ok(frame, sizeof(*frame)))

	if (!user_access_begin(frame, sizeof(*frame)))

		return -EFAULT;



	put_user_try {

		put_user_ex(sig, &frame->sig);

		put_user_ex(&frame->info, &frame->pinfo);

		put_user_ex(&frame->uc, &frame->puc);

	unsafe_put_user(sig, &frame->sig, Efault);

	unsafe_put_user(&frame->info, &frame->pinfo, Efault);

	unsafe_put_user(&frame->uc, &frame->puc, Efault);



	/* Create the ucontext.  */

	if (static_cpu_has(X86_FEATURE_XSAVE))

			put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);

		unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);

	else

			put_user_ex(0, &frame->uc.uc_flags);

		put_user_ex(0, &frame->uc.uc_link);

		save_altstack_ex(&frame->uc.uc_stack, regs->sp);

		unsafe_put_user(0, &frame->uc.uc_flags, Efault);

	unsafe_put_user(0, &frame->uc.uc_link, Efault);

	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);



	/* Set up to return from userspace.  */

	restorer = current->mm->context.vdso +

		vdso_image_32.sym___kernel_rt_sigreturn;

	if (ksig->ka.sa.sa_flags & SA_RESTORER)

		restorer = ksig->ka.sa.sa_restorer;

		put_user_ex(restorer, &frame->pretcode);

	unsafe_put_user(restorer, &frame->pretcode, Efault);



	/*

	 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
@@ -395,8 +394,8 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
	 * reasons and because gdb uses it as a signature to notice

	 * signal handler stack frames.

	 */

		put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);

	} put_user_catch(err);

	unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);

	user_access_end();

	

	err |= copy_siginfo_to_user(&frame->info, &ksig->info);

	err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
@@ -419,6 +418,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
	regs->cs = __USER_CS;



	return 0;

Efault:

	user_access_end();

	return -EFAULT;

}

#else /* !CONFIG_X86_32 */

static unsigned long frame_uc_flags(struct pt_regs *regs)
@@ -444,6 +446,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
	unsigned long uc_flags;

	int err = 0;



	/* x86-64 should always use SA_RESTORER. */

	if (!(ksig->ka.sa.sa_flags & SA_RESTORER))

		return -EFAULT;



	frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);



	if (!access_ok(frame, sizeof(*frame)))
@@ -455,23 +461,18 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
	}



	uc_flags = frame_uc_flags(regs);

	if (!user_access_begin(frame, sizeof(*frame)))

		return -EFAULT;



	put_user_try {

	/* Create the ucontext.  */

		put_user_ex(uc_flags, &frame->uc.uc_flags);

		put_user_ex(0, &frame->uc.uc_link);

		save_altstack_ex(&frame->uc.uc_stack, regs->sp);

	unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);

	unsafe_put_user(0, &frame->uc.uc_link, Efault);

	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);



	/* Set up to return from userspace.  If provided, use a stub

	   already in userspace.  */

		/* x86-64 should always use SA_RESTORER. */

		if (ksig->ka.sa.sa_flags & SA_RESTORER) {

			put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);

		} else {

			/* could use a vstub here */

			err |= -EFAULT;

		}

	} put_user_catch(err);

	unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);

	user_access_end();



	err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);

	err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
@@ -515,6 +516,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 
		force_valid_ss(regs);



	return 0;



Efault:

	user_access_end();

	return -EFAULT;

}

#endif /* CONFIG_X86_32 */

include/linux/signal.h

+4 −4
Original line number Diff line number Diff line
@@ -444,12 +444,12 @@ void signals_init(void); 
int restore_altstack(const stack_t __user *);

int __save_altstack(stack_t __user *, unsigned long);



#define save_altstack_ex(uss, sp) do { \

#define unsafe_save_altstack(uss, sp, label) do { \

	stack_t __user *__uss = uss; \

	struct task_struct *t = current; \

	put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \

	put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \

	put_user_ex(t->sas_ss_size, &__uss->ss_size); \

	unsafe_put_user((void __user *)t->sas_ss_sp, &__uss->ss_sp, label); \

	unsafe_put_user(t->sas_ss_flags, &__uss->ss_flags, label); \

	unsafe_put_user(t->sas_ss_size, &__uss->ss_size, label); \

	if (t->sas_ss_flags & SS_AUTODISARM) \

		sas_ss_reset(t); \

} while (0);