Commit-ID: 6fdc6dd90272ce7e75d744f71535cfbd8d77da81 Gitweb: http://git.kernel.org/tip/6fdc6dd90272ce7e75d744f71535cfbd8d77da81 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Mon, 10 Apr 2017 17:14:28 +0200 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Mon, 10 Apr 2017 18:31:41 +0200 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@xxxxxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Mathias Krause <minipli@xxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20170410151723.602367196@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- arch/x86/include/asm/elf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 9d49c18..3762536 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); \ } \ -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html