From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@amacapital.net>,
Mathias Krause <minipli@googlemail.com>,
stable@vger.kernel.org
Subject: [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup
Date: Mon, 10 Apr 2017 17:14:28 +0200 [thread overview]
Message-ID: <20170410151723.602367196@linutronix.de> (raw)
In-Reply-To: 20170410151426.808543816@linutronix.de
[-- Attachment #1: x86-vdso--Plug-race-between-mapping-and-ELF-header-setup.patch --]
[-- Type: text/plain, Size: 1131 bytes --]
The vsyscall32 sysctl can racy against a concurrent fork when it switches
from disabled to enabled:
arch_setup_additional_pages()
if (vdso32_enabled)
--> No mapping
sysctl.vsysscall32()
--> vdso32_enabled = true
create_elf_tables()
ARCH_DLINFO_IA32
if (vdso32_enabled) {
--> Add VDSO entry with NULL pointer
Make ARCH_DLINFO_IA32 check whether the VDSO mapping has been set up for
the newly forked process or not.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: stable@vger.kernel.org
---
arch/x86/include/asm/elf.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -287,7 +287,7 @@ struct task_struct;
#define ARCH_DLINFO_IA32 \
do { \
- if (vdso32_enabled) { \
+ if (VDSO_CURRENT_BASE) { \
NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY); \
NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_CURRENT_BASE); \
} \
next prev parent reply other threads:[~2017-04-10 15:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-10 15:14 [patch 0/3] x86/vdso: Fix enable inconsistencies and cleanup Thomas Gleixner
2017-04-10 15:14 ` [patch 1/3] x86/vdso: Ensure vdso32_enabled gets set to valid values only Thomas Gleixner
2017-04-10 16:34 ` [tip:x86/urgent] " tip-bot for Mathias Krause
2017-04-10 15:14 ` Thomas Gleixner [this message]
2017-04-10 15:56 ` [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup Andy Lutomirski
2017-04-10 16:34 ` [tip:x86/urgent] " tip-bot for Thomas Gleixner
2017-04-10 15:14 ` [patch 3/3] x86/vdso: Sanitize vdso*_enabled handling Thomas Gleixner
2017-04-10 15:55 ` Andy Lutomirski
2017-04-10 16:25 ` Thomas Gleixner
-- strict thread matches above, loose matches on Subject: below --
2017-04-05 20:36 [PATCH] x86/vdso: ensure vdso32_enabled gets set to valid values only Mathias Krause
2017-04-06 15:59 ` Andy Lutomirski
2017-04-10 13:13 ` Thomas Gleixner
2017-04-10 13:41 ` Thomas Gleixner
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