This is a note to let you know that I've just added the patch titled

selftests/x86: Add tests for the STR and SLDT instructions

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: selftests-x86-add-tests-for-the-str-and-sldt-instructions.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From a9e017d5619eb371460c8e516f4684def62bef3a Mon Sep 17 00:00:00 2001

From: Ricardo Neri ricardo.neri-calderon@linux.intel.com Date: Sun, 5 Nov 2017 18:27:57 -0800 Subject: selftests/x86: Add tests for the STR and SLDT instructions

From: Ricardo Neri ricardo.neri-calderon@linux.intel.com

commit a9e017d5619eb371460c8e516f4684def62bef3a upstream.

The STR and SLDT instructions are not valid when running on virtual-8086 mode and generate an invalid operand exception. These two instructions are protected by the Intel User-Mode Instruction Prevention (UMIP) security feature. In protected mode, if UMIP is enabled, these instructions generate a general protection fault if called from CPL > 0. Linux traps the general protection fault and emulates the instructions sgdt, sidt and smsw; but not str and sldt.

These tests are added to verify that the emulation code does not emulate these two instructions but the expected invalid operand exception is seen.

Tests fallback to exit with INT3 in case emulation does happen.

Signed-off-by: Ricardo Neri ricardo.neri-calderon@linux.intel.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Andy Lutomirski luto@kernel.org Cc: Borislav Petkov bp@alien8.de Cc: Borislav Petkov bp@suse.de Cc: Brian Gerst brgerst@gmail.com Cc: Chen Yucong slaoub@gmail.com Cc: Chris Metcalf cmetcalf@mellanox.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Fenghua Yu fenghua.yu@intel.com Cc: H. Peter Anvin hpa@zytor.com Cc: Huang Rui ray.huang@amd.com Cc: Jiri Slaby jslaby@suse.cz Cc: Jonathan Corbet corbet@lwn.net Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Michael S. Tsirkin mst@redhat.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Paul Gortmaker paul.gortmaker@windriver.com Cc: Peter Zijlstra peterz@infradead.org Cc: Ravi V. Shankar ravi.v.shankar@intel.com Cc: Shuah Khan shuah@kernel.org Cc: Tony Luck tony.luck@intel.com Cc: Vlastimil Babka vbabka@suse.cz Cc: ricardo.neri@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-13-git-send-email-ricardo.neri-cal... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- tools/testing/selftests/x86/entry_from_vm86.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/x86/entry_from_vm86.c +++ b/tools/testing/selftests/x86/entry_from_vm86.c @@ -111,6 +111,11 @@ asm ( "smsw %ax\n\t" "mov %ax, (2080)\n\t" "int3\n\t" + "vmcode_umip_str:\n\t" + "str %eax\n\t" + "vmcode_umip_sldt:\n\t" + "sldt %eax\n\t" + "int3\n\t" ".size vmcode, . - vmcode\n\t" "end_vmcode:\n\t" ".code32\n\t" @@ -119,7 +124,8 @@ asm (

extern unsigned char vmcode[], end_vmcode[]; extern unsigned char vmcode_bound[], vmcode_sysenter[], vmcode_syscall[], - vmcode_sti[], vmcode_int3[], vmcode_int80[], vmcode_umip[]; + vmcode_sti[], vmcode_int3[], vmcode_int80[], vmcode_umip[], + vmcode_umip_str[], vmcode_umip_sldt[];

/* Returns false if the test was skipped. */ static bool do_test(struct vm86plus_struct *v86, unsigned long eip, @@ -226,6 +232,16 @@ void do_umip_tests(struct vm86plus_struc printf("[FAIL]\tAll the results of SIDT should be the same.\n"); else printf("[PASS]\tAll the results from SIDT are identical.\n"); + + sethandler(SIGILL, sighandler, 0); + do_test(vm86, vmcode_umip_str - vmcode, VM86_SIGNAL, 0, + "STR instruction"); + clearhandler(SIGILL); + + sethandler(SIGILL, sighandler, 0); + do_test(vm86, vmcode_umip_sldt - vmcode, VM86_SIGNAL, 0, + "SLDT instruction"); + clearhandler(SIGILL); }

int main(void)

Patches currently in stable-queue which might be from ricardo.neri-calderon@linux.intel.com are

queue-4.4/selftests-x86-add-tests-for-the-str-and-sldt-instructions.patch queue-4.4/selftests-x86-add-tests-for-user-mode-instruction-prevention.patch