From 76fc5e7b2355af167dea1a32e93c57fc37900a5b Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Fri, 4 Sep 2015 17:00:43 -0700 Subject: x86/vm86: Block non-root vm86(old) if mmap_min_addr != 0 vm86 exposes an interesting attack surface against the entry code. Since vm86 is mostly useless anyway if mmap_min_addr != 0, just turn it off in that case. There are some reports that vbetool can work despite setting mmap_min_addr to zero. This shouldn't break that use case, as CAP_SYS_RAWIO already overrides mmap_min_addr. Suggested-by: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Arjan van de Ven Cc: Austin S Hemmelgarn Cc: Borislav Petkov Cc: Brian Gerst Cc: Josh Boyer Cc: Kees Cook Cc: Matthew Garrett Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Stas Sergeev Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- tools/testing/selftests/x86/entry_from_vm86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c index 9a43a59a9bb4..421c607a8856 100644 --- a/tools/testing/selftests/x86/entry_from_vm86.c +++ b/tools/testing/selftests/x86/entry_from_vm86.c @@ -116,8 +116,9 @@ static bool do_test(struct vm86plus_struct *v86, unsigned long eip, v86->regs.eip = eip; ret = vm86(VM86_ENTER, v86); - if (ret == -1 && errno == ENOSYS) { - printf("[SKIP]\tvm86 not supported\n"); + if (ret == -1 && (errno == ENOSYS || errno == EPERM)) { + printf("[SKIP]\tvm86 %s\n", + errno == ENOSYS ? "not supported" : "not allowed"); return false; } -- cgit