[PATCH v7 10/10] powerpc/signal: Use __get_user() to copy sigset_t
From: Christopher M. Riedl <hidden>
Date: 2021-02-27 01:16:36
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- 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 d8dd76b1dc94..1393876f3814 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 75ee918a120a..c505b444a613 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 00c907022707..debe88055f38 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);
--
2.26.1