This is a note to let you know that I've just added the patch titled selftests/x86/ldt_get: Add a few additional tests for limits to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: selftests-x86-ldt_get-add-a-few-additional-tests-for-limits.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Dec 6 17:39:55 CET 2017 From: Andy Lutomirski <luto@xxxxxxxxxx> Date: Sat, 4 Nov 2017 04:19:52 -0700 Subject: selftests/x86/ldt_get: Add a few additional tests for limits From: Andy Lutomirski <luto@xxxxxxxxxx> [ Upstream commit fec8f5ae1715a01c72ad52cb2ecd8aacaf142302 ] We weren't testing the .limit and .limit_in_pages fields very well. Add more tests. This addition seems to trigger the "bits 16:19 are undefined" issue that was fixed in an earlier patch. I think that, at least on my CPU, the high nibble of the limit ends in LAR bits 16:19. Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bpetkov@xxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/5601c15ea9b3113d288953fd2838b18bedf6bc67.1509794321.git.luto@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/x86/ldt_gdt.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) --- a/tools/testing/selftests/x86/ldt_gdt.c +++ b/tools/testing/selftests/x86/ldt_gdt.c @@ -360,9 +360,24 @@ static void do_simple_tests(void) install_invalid(&desc, false); desc.seg_not_present = 0; - desc.read_exec_only = 0; desc.seg_32bit = 1; + desc.read_exec_only = 0; + desc.limit = 0xfffff; + install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB); + + desc.limit_in_pages = 1; + + install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB | AR_G); + desc.read_exec_only = 1; + install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P | AR_DB | AR_G); + desc.contents = 1; + desc.read_exec_only = 0; + install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G); + desc.read_exec_only = 1; + install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G); + + desc.limit = 0; install_invalid(&desc, true); } Patches currently in stable-queue which might be from luto@xxxxxxxxxx are queue-4.9/selftests-x86-ldt_get-add-a-few-additional-tests-for-limits.patch queue-4.9/x86-entry-use-syscall_define-macros-for-sys_modify_ldt.patch queue-4.9/x86-fpu-set-the-xcomp_bv-when-we-fake-up-a-xsaves-area.patch