From befef5ef70f959cd51694298c4370557e5d846cf Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 2 Nov 2017 00:58:58 -0700 Subject: [PATCH 086/242] x86/entry/64: Remove the restore_c_regs_and_iret label MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 The only user was the 64-bit opportunistic SYSRET failure path, and that path didn't really need it. This change makes the opportunistic SYSRET code a bit more straightforward and gets rid of the label. Signed-off-by: Andy Lutomirski Reviewed-by: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/be3006a7ad3326e3458cf1cc55d416252cbe1986.1509609304.git.luto@kernel.org Signed-off-by: Ingo Molnar (cherry picked from commit 9da78ba6b47b46428cfdfc0851511ab29c869798) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit 629c8b858cbe72e88e7f44a8f10e1b434ab80721) Signed-off-by: Fabian Grünbichler --- arch/x86/entry/entry_64.S | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 34adfe0221d2..fac354ddf056 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -245,7 +245,6 @@ entry_SYSCALL64_slow_path: call do_syscall_64 /* returns with IRQs disabled */ return_from_SYSCALL_64: - RESTORE_EXTRA_REGS TRACE_IRQS_IRETQ /* we're about to change IF */ /* @@ -314,6 +313,7 @@ return_from_SYSCALL_64: */ syscall_return_via_sysret: /* rcx and r11 are already restored (see code above) */ + RESTORE_EXTRA_REGS RESTORE_C_REGS_EXCEPT_RCX_R11 movq RSP(%rsp), %rsp UNWIND_HINT_EMPTY @@ -321,7 +321,7 @@ syscall_return_via_sysret: opportunistic_sysret_failed: SWAPGS - jmp restore_c_regs_and_iret + jmp restore_regs_and_iret END(entry_SYSCALL_64) ENTRY(stub_ptregs_64) @@ -638,7 +638,6 @@ retint_kernel: */ GLOBAL(restore_regs_and_iret) RESTORE_EXTRA_REGS -restore_c_regs_and_iret: RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 INTERRUPT_RETURN -- 2.14.2