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authorThomas Gleixner <tglx@linutronix.de>2017-04-10 17:14:28 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-04-10 18:31:41 +0200
commit6fdc6dd90272ce7e75d744f71535cfbd8d77da81 (patch)
treea6c19e22befb56580fd103b4e855ab9567ff69ac /arch
parentc06989da39cdb10604d572c8c7ea8c8c97f3c483 (diff)
downloadlinux-6fdc6dd90272ce7e75d744f71535cfbd8d77da81.tar.bz2
x86/vdso: Plug race between mapping and ELF header setup
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> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mathias Krause <minipli@googlemail.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20170410151723.602367196@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/elf.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 9d49c18b5ea9..3762536619f8 100644
--- 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); \
} \