From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 4 Dec 2017 15:07:43 +0100 Subject: [PATCH] x86/mm/pti: Force entry through trampoline when PTI active MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 Force the entry through the trampoline only when PTI is active. Otherwise go through the normal entry code. Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar (cherry picked from commit 8d4b067895791ab9fdb1aadfc505f64d71239dd2) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit 9ae1ea4821648be179a96fe65b3ed4bd111a5c98) Signed-off-by: Fabian Grünbichler --- arch/x86/kernel/cpu/common.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 623ba3635793..99f37d1636ff 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1340,7 +1340,10 @@ void syscall_init(void) (entry_SYSCALL_64_trampoline - _entry_trampoline); wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS); - wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline); + if (static_cpu_has(X86_FEATURE_PTI)) + wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline); + else + wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64); #ifdef CONFIG_IA32_EMULATION wrmsrl(MSR_CSTAR, (unsigned long)entry_SYSCALL_compat); -- 2.14.2