From: bob picco <[email protected]>

do_sigaltstack expects the stack we are returning to. An issue will manifest
with an alternate stack. That is, a sigaltstack followed by a sigaction
(aka. rt_sigaction) with SA_ONSTACK for flags will sigsegv. do_sigaltstack
returns -EPERM having found on_sig_stack to be true and a sigsegv results.

Let's teach do_rt_sigreturn to provide do_sigaltstack with our target stack.

Signed-off-by: Bob Picco <[email protected]>
cc: [email protected]
---
 arch/sparc/kernel/signal_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index 1f905f6..f572586 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -295,7 +295,7 @@ void do_rt_sigreturn(struct pt_regs *regs)
                err |= restore_fpu_state(regs, fpu_save);
 
        err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
-       err |= do_sigaltstack(&sf->stack, NULL, (unsigned long)sf);
+       err |= do_sigaltstack(&sf->stack, NULL, regs->u_regs[UREG_FP]);
 
        if (err)
                goto segv;
-- 
1.7.10

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