diff options
| author | Al Viro <viro@ZenIV.linux.org.uk> | 2013-09-01 20:35:01 +0100 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-09-01 14:16:33 -0700 |
| commit | bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 (patch) | |
| tree | 1ccdf876f778bd986a6238d379ee9e9981ed98dc | |
| parent | 7263dda41b5a28ae6566fd126d9b06ada73dd721 (diff) | |
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
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@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.8+
Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org
| -rw-r--r-- | arch/x86/ia32/ia32_signal.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/signal.c | 6 | ||||
| -rw-r--r-- | include/linux/compat.h | 7 | ||||
| -rw-r--r-- | 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 bccfca68430e..665a730307f2 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -457,7 +457,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, 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 (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index cf913587d4dd..d859eea07db7 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -358,7 +358,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 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); @@ -423,7 +423,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, 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. */ @@ -490,7 +490,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig, 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 (ksig->ka.sa.sa_flags & SA_RESTORER) { diff --git a/include/linux/compat.h b/include/linux/compat.h index 7f0c1dd09079..ec1aee4aec9c 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -669,6 +669,13 @@ 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); asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid, struct compat_timespec __user *interval); diff --git a/include/linux/signal.h b/include/linux/signal.h index d897484730c0..2ac423bdb676 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -434,6 +434,14 @@ 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); + #ifdef CONFIG_PROC_FS struct seq_file; extern void render_sigset_t(struct seq_file *, const char *, sigset_t *); |