[3.5.y.z extended stable] Patch "xtensa: don't use alternate signal stack on threads" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Tue Nov 12 12:45:28 UTC 2013


This is a note to let you know that I have just added a patch titled

    xtensa: don't use alternate signal stack on threads

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 5072ed5e2462661ced0733e3f27cf5f983f52b70 Mon Sep 17 00:00:00 2001
From: Baruch Siach <baruch at tkos.co.il>
Date: Tue, 15 Oct 2013 02:22:43 +0400
Subject: xtensa: don't use alternate signal stack on threads

commit cba9a90053e3b7973eff4f1946f33032e98eeed5 upstream.

According to create_thread(3): "The new thread does not inherit the creating
thread's alternate signal stack". Since commit f9a3879a (Fix sigaltstack
corruption among cloned threads), current->sas_ss_size is set to 0 for cloned
processes sharing VM with their parent. Don't use the (nonexistent) alternate
signal stack in this case. This has been broken since commit 29c4dfd9 ([XTENSA]
Remove non-rt signal handling).

Fixes the SA_ONSTACK part of the nptl/tst-cancel20 test from uClibc.

Signed-off-by: Baruch Siach <baruch at tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc at gmail.com>
Signed-off-by: Chris Zankel <chris at zankel.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/xtensa/kernel/signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
index efe4e85..163cfc8 100644
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -342,7 +342,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,

 	sp = regs->areg[1];

-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) {
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
 		sp = current->sas_ss_sp + current->sas_ss_size;
 	}

--
1.8.3.2





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