[PATCH] FRV: Fix sigaltstack handling for RT signals

[David Howells]

The attached patch fixes sigaltstack handling for RT signal return. It was
reading a userspace struct into kernel space and then passing the kernel copy
to a generic signalling routine which then assumed it had been passed a
userspace pointer...

Signed-Off-By: David Howells <dhowells@xxxxxxxxxx>
Signed-Off-By: Alexander Viro <aviro@xxxxxxxxxx>
---
warthog>diffstat frv-sigaltstk-2611rc3.diff 
 signal.c |   11 +----------
 1 files changed, 1 insertion(+), 10 deletions(-)

diff -uNrp /warthog/kernels/linux-2.6.11-rc3/arch/frv/kernel/signal.c linux-2.6.11-rc3-frv/arch/frv/kernel/signal.c
--- /warthog/kernels/linux-2.6.11-rc3/arch/frv/kernel/signal.c	2005-02-04 11:49:30.000000000 +0000
+++ linux-2.6.11-rc3-frv/arch/frv/kernel/signal.c	2005-02-11 12:46:40.369651032 +0000
@@ -242,18 +242,9 @@ asmlinkage int sys_rt_sigreturn(void)
 	if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
 		goto badframe;
 
-	if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
+	if (do_sigaltstack(&frame->uc.uc_stack, NULL, __frame->sp) == -EFAULT)
 		goto badframe;
 
-	/* It is more difficult to avoid calling this function than to
-	 * call it and ignore errors.  */
-	/*
-	 * THIS CANNOT WORK! "&st" is a kernel address, and "do_sigaltstack()"
-	 * takes a user address (and verifies that it is a user address). End
-	 * result: it does exactly _nothing_.
-	 */
-	do_sigaltstack(&st, NULL, __frame->sp);
-
 	return gr8;
 
 badframe:
-
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