Commit d3ccc978 authored by Christopher M. Riedl's avatar Christopher M. Riedl Committed by Michael Ellerman
Browse files

powerpc/signal: Use __get_user() to copy sigset_t 



Usually sigset_t is exactly 8B which is a "trivial" size and does not
warrant using __copy_from_user(). Use __get_user() directly in
anticipation of future work to remove the trivial size optimizations
from __copy_from_user().

The ppc32 implementation of get_sigset_t() previously called
copy_from_user() which, unlike __copy_from_user(), calls access_ok().
Replacing this w/ __get_user() (no access_ok()) is fine here since both
callsites in signal_32.c are preceded by an earlier access_ok().

Signed-off-by: default avatarChristopher M. Riedl <cmr@codefail.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de
parent 0f92433b

arch/powerpc/kernel/signal.h

+7 −0
Original line number Diff line number Diff line
@@ -19,6 +19,13 @@ extern int handle_signal32(struct ksignal *ksig, sigset_t *oldset, 
extern int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,

			      struct task_struct *tsk);



static inline int __get_user_sigset(sigset_t *dst, const sigset_t __user *src)

{

	BUILD_BUG_ON(sizeof(sigset_t) != sizeof(u64));



	return __get_user(dst->sig[0], (u64 __user *)&src->sig[0]);

}



#ifdef CONFIG_VSX

extern unsigned long copy_vsx_to_user(void __user *to,

				      struct task_struct *task);

arch/powerpc/kernel/signal_32.c

+1 −1
Original line number Diff line number Diff line
@@ -144,7 +144,7 @@ static inline int restore_general_regs(struct pt_regs *regs, 


static inline int get_sigset_t(sigset_t *set, const sigset_t __user *uset)

{

	return copy_from_user(set, uset, sizeof(*uset));

	return __get_user_sigset(set, uset);

}



#define to_user_ptr(p)		((unsigned long)(p))

arch/powerpc/kernel/signal_64.c

+2 −2
Original line number Diff line number Diff line
@@ -708,7 +708,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, 
	 * We kill the task with a SIGSEGV in this situation.

	 */



	if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))

	if (__get_user_sigset(&set, &new_ctx->uc_sigmask))

		do_exit(SIGSEGV);

	set_current_blocked(&set);
@@ -747,7 +747,7 @@ SYSCALL_DEFINE0(rt_sigreturn) 
	if (!access_ok(uc, sizeof(*uc)))

		goto badframe;



	if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))

	if (__get_user_sigset(&set, &uc->uc_sigmask))

		goto badframe;

	set_current_blocked(&set);