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[PATCH 5/5] mips: do_sigaltstack() expects userland pointers

To: ralf@linux-mips.org
Subject: [PATCH 5/5] mips: do_sigaltstack() expects userland pointers
From: Al Viro <viro@ftp.linux.org.uk>
Date: Tue, 28 Sep 2010 18:50:57 +0100
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Resent-date: Thu, 14 Oct 2010 11:41:54 +0100
Resent-from: ralf@linux-mips.org
Resent-message-id: <20101014104154.GE28911@linux-mips.org>
Resent-to: linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Heirloom mailx 12.4 7/29/08
o32 compat does the right thing, native and n32 compat do not...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/mips/kernel/signal.c     |    5 +----
 arch/mips/kernel/signal_n32.c |    5 +++++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 604f077..5922342 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 2c5df81..ee24d81 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 ...
-- 
1.5.6.5

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