3.8.13.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> commit bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 upstream. For performance reasons, when SMAP is in use, SMAP is left open for an entire put_user_try { ... } put_user_catch(); block, however, calling __put_user() in the middle of that block will close SMAP as the STAC..CLAC constructs intentionally do not nest. Furthermore, using __put_user() rather than put_user_ex() here is bad for performance. Thus, introduce new [compat_]save_altstack_ex() helpers that replace __[compat_]save_altstack() for x86, being currently the only architecture which supports put_user_try { ... } put_user_catch(). Reported-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@xxxxxxxxxxxxxx [ kamal: backport to 3.8 (context) ] Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> --- arch/x86/ia32/ia32_signal.c | 2 +- arch/x86/kernel/signal.c | 6 +++--- include/linux/compat.h | 7 +++++++ include/linux/signal.h | 8 ++++++++ 4 files changed, 19 insertions(+), 4 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index a1daf4a..fb53906 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -467,7 +467,7 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); + compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); if (ka->sa.sa_flags & SA_RESTORER) restorer = ka->sa.sa_restorer; diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index d6bf1f3..1697f73 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -364,7 +364,7 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __save_altstack(&frame->uc.uc_stack, regs->sp); + save_altstack_ex(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. */ restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn); @@ -429,7 +429,7 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __save_altstack(&frame->uc.uc_stack, regs->sp); + save_altstack_ex(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. If provided, use a stub already in userspace. */ @@ -496,7 +496,7 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); + compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); put_user_ex(0, &frame->uc.uc__pad0); if (ka->sa.sa_flags & SA_RESTORER) { diff --git a/include/linux/compat.h b/include/linux/compat.h index dec7e2d..98ac3c5 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -648,6 +648,13 @@ asmlinkage long compat_sys_sigaltstack(const compat_stack_t __user *uss_ptr, int compat_restore_altstack(const compat_stack_t __user *uss); int __compat_save_altstack(compat_stack_t __user *, unsigned long); +#define compat_save_altstack_ex(uss, sp) do { \ + compat_stack_t __user *__uss = uss; \ + struct task_struct *t = current; \ + put_user_ex(ptr_to_compat((void __user *)t->sas_ss_sp), &__uss->ss_sp); \ + put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_size, &__uss->ss_size); \ +} while (0); #endif asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid, diff --git a/include/linux/signal.h b/include/linux/signal.h index 0a89ffc..b50aa60 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -388,4 +388,12 @@ 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 { \ + 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(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_size, &__uss->ss_size); \ +} while (0); + #endif /* _LINUX_SIGNAL_H */ -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html