| From | Ben Hutchings <> | Date | Sun, 16 Jul 2017 14:56:38 +0100 | Subject | [PATCH 3.2 75/95] x86/vdso: Plug race between mapping and ELF header setup |
| |
3.2.91-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Gleixner <tglx@linutronix.de>
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@linutronix.de> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mathias Krause <minipli@googlemail.com> Link: http://lkml.kernel.org/r/20170410151723.602367196@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: change the flag passed to ARCH_DLINFO_IA32()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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 @@ -298,7 +298,7 @@ do { \ #define AT_SYSINFO 32 -#define COMPAT_ARCH_DLINFO ARCH_DLINFO_IA32(sysctl_vsyscall32) +#define COMPAT_ARCH_DLINFO ARCH_DLINFO_IA32(VDSO_CURRENT_BASE) #define COMPAT_ELF_ET_DYN_BASE (TASK_UNMAPPED_BASE + 0x1000000)
|