From 26e89424fe3c13d437f960736a7b925f3953cad6 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Sat, 4 Nov 2017 04:19:52 -0700 Subject: [PATCH 116/242] selftests/x86/ldt_get: Add a few additional tests for limits MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 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 Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/5601c15ea9b3113d288953fd2838b18bedf6bc67.1509794321.git.luto@kernel.org Signed-off-by: Ingo Molnar (cherry picked from commit fec8f5ae1715a01c72ad52cb2ecd8aacaf142302) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit a1cdabf77d7ed9ba02697ad8beb04adf46a7c7b8) Signed-off-by: Fabian Grünbichler --- tools/testing/selftests/x86/ldt_gdt.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c index 05d0d6f49c2c..8e290c9b2c3f 100644 --- a/tools/testing/selftests/x86/ldt_gdt.c +++ b/tools/testing/selftests/x86/ldt_gdt.c @@ -403,9 +403,24 @@ 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); } -- 2.14.2