linux-kernel - [tip: x86/urgent] x86/doublefault/32: Fix stack canaries in the double fault handler

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Date:   Thu, 21 Nov 2019 20:14:26 -0000
From:   "tip-bot2 for Andy Lutomirski" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Andy Lutomirski <luto@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, stable@...nel.org,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/urgent] x86/doublefault/32: Fix stack canaries in the
 double fault handler

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     3580d0b29cab08483f84a16ce6a1151a1013695f
Gitweb:        https://git.kernel.org/tip/3580d0b29cab08483f84a16ce6a1151a1013695f
Author:        Andy Lutomirski <luto@...nel.org>
AuthorDate:    Thu, 21 Nov 2019 11:50:12 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 21 Nov 2019 19:37:42 +01:00

x86/doublefault/32: Fix stack canaries in the double fault handler

The double fault TSS was missing GS setup, which is needed for stack
canaries to work.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: stable@...nel.org
---
 arch/x86/kernel/doublefault.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/doublefault.c b/arch/x86/kernel/doublefault.c
index 0b8cedb..d5c9b13 100644
--- a/arch/x86/kernel/doublefault.c
+++ b/arch/x86/kernel/doublefault.c
@@ -65,6 +65,9 @@ struct x86_hw_tss doublefault_tss __cacheline_aligned = {
 	.ss		= __KERNEL_DS,
 	.ds		= __USER_DS,
 	.fs		= __KERNEL_PERCPU,
+#ifndef CONFIG_X86_32_LAZY_GS
+	.gs		= __KERNEL_STACK_CANARY,
+#endif
 
 	.__cr3		= __pa_nodebug(swapper_pg_dir),
 };