From d3ccc9781560af051554017c702631560bdc0811 Mon Sep 17 00:00:00 2001 From: "Christopher M. Riedl" Date: Fri, 26 Feb 2021 19:12:59 -0600 Subject: [PATCH] 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: Christopher M. Riedl Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de --- arch/powerpc/kernel/signal.h | 7 +++++++ arch/powerpc/kernel/signal_32.c | 2 +- arch/powerpc/kernel/signal_64.c | 4 ++-- 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h index d8dd76b1dc9404..1393876f38143f 100644 --- a/arch/powerpc/kernel/signal.h +++ b/arch/powerpc/kernel/signal.h @@ -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); diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 75ee918a120a5e..c505b444a6131e 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -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)) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index e7d612e8236385..e10459f11f8e03 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -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);