3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <v...@zeniv.linux.org.uk>
commit fae2ae2a900a5c7bb385fe4075f343e7e2d5daa2 upstream.
If a signal handler is executed on altstack and another signal comes,
we will end up with rt_sigreturn() on return from the second handler
getting -EPERM from do_sigaltstack(). It's perfectly OK, since we
are not asking to change the settings; in fact, they couldn't have been
changed during the second handler execution exactly because we'd been
on altstack all along. 64bit sigreturn on sparc treats any error from
do_sigaltstack() as "SIGSEGV now"; we need to switch to the same semantics
we are using on other architectures.
Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
arch/sparc/kernel/signal_64.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index 867de2f..689e1ba 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -295,9 +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);
-
- if (err)
+ if (err || do_sigaltstack(&sf->stack, NULL, (unsigned long)sf) ==
-EFAULT)
goto segv;
err |= __get_user(rwin_save, &sf->rwin_save);
--
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