MIPS: do_sigaltstack() expects userland pointers

o32 compat does the right thing, native and n32 compat do not...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1700/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 6 insertions, 4 deletions

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 604f077bb5bf..5922342bca39 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -390,7 +390,6 @@ asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 {
         struct rt_sigframe __user *frame;
         sigset_t set;
-        stack_t st;
         int sig;
 
         frame = (struct rt_sigframe __user *) regs.regs[29];
@@ -411,11 +410,9 @@ asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
         else if (sig)
                 force_sig(sig, current);
 
-        if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
-                goto badframe;
         /* It is more difficult to avoid calling this function than to
            call it and ignore errors.  */
-        do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
+        do_sigaltstack(&frame->rs_uc.uc_stack, NULL, regs.regs[29]);
 
         /*
          * Don't let your children do this ...
diff --git a/arch/mips/kernel/signal_n32.c b/arch/mips/kernel/signal_n32.c
index 2c5df818c65a..ee24d814d5b9 100644
--- a/arch/mips/kernel/signal_n32.c
+++ b/arch/mips/kernel/signal_n32.c
@@ -109,6 +109,7 @@ asmlinkage int sysn32_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
 asmlinkage void sysn32_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 {
         struct rt_sigframe_n32 __user *frame;
+        mm_segment_t old_fs;
         sigset_t set;
         stack_t st;
         s32 sp;
@@ -143,7 +144,11 @@ asmlinkage void sysn32_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 
         /* It is more difficult to avoid calling this function than to
            call it and ignore errors.  */
+        old_fs = get_fs();
+        set_fs(KERNEL_DS);
         do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
+        set_fs(old_fs);
+
 
         /*
          * Don't let your children do this ...