This is a note to let you know that I've just added the patch titled
x86/vdso: Plug race between mapping and ELF header setup
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-vdso-plug-race-between-mapping-and-elf-header-setup.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6fdc6dd90272ce7e75d744f71535cfbd8d77da81 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Mon, 10 Apr 2017 17:14:28 +0200
Subject: x86/vdso: Plug race between mapping and ELF header setup
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 6fdc6dd90272ce7e75d744f71535cfbd8d77da81 upstream.
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@xxxxxxxxxxxxx>
Acked-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Mathias Krause <minipli@xxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170410151723.602367196@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -278,7 +278,7 @@ 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); \
} \
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-4.4/x86-vdso-ensure-vdso32_enabled-gets-set-to-valid-values-only.patch
queue-4.4/x86-vdso-plug-race-between-mapping-and-elf-header-setup.patch
queue-4.4/cgroup-kthread-close-race-window-where-new-kthreads-can-be-migrated-to-non-root-cgroups.patch
queue-4.4/perf-x86-avoid-exposing-wrong-stale-data-in-intel_pmu_lbr_read_32.patch