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2015-10-31selftests/x86: Add a fork() to entry_from_vm86 to catch fork bugsAndy Lutomirski1-0/+4
Mere possession of vm86 state is strange. Make sure that nothing gets corrupted if we fork after calling vm86(). Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Stas Sergeev <stsp@list.ru> Link: http://lkml.kernel.org/r/08f83295460a80e41dc5e3e81ec40d6844d316f5.1446270067.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-05x86/vm86: Block non-root vm86(old) if mmap_min_addr != 0Andy Lutomirski1-2/+3
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 <torvalds@linux-foundation.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Austin S Hemmelgarn <ahferroin7@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Josh Boyer <jwboyer@fedoraproject.org> Cc: Kees Cook <keescook@chromium.org> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stas Sergeev <stsp@list.ru> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-31selftests/x86/vm86: Fix entry_from_vm86 test on 64-bit kernelsAndy Lutomirski1-4/+7
The test failed due to an oversight on my part when run on a 64-bit kernel. vm86 isn't expected to work at all, and I mistakenly failed one part of the test because no signal was delivered. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/502c8bef877b33fe4943885ded6125dfcc7892db.1438205722.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-21x86/selftests, x86/vm86: Improve entry_from_vm86 selftestAndy Lutomirski1-8/+124
The entry_from_vm86 selftest was very weak. Improve it: test more types of kernel entries from vm86 mode and test them more carefully. While we're at it, try to improve behavior on non-SEP CPUs. The old code was buggy because I misunderstood the intended semantics of #UD in vm86, so I didn't handle a possible signal. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/d8ef1d7368ac70d8342481563ed50f9a7d2eea6f.1436492057.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-30x86/asm/entry/32, selftests: Add a selftest for kernel entries from VM86 modeAndy Lutomirski1-0/+114
Test a couple of special cases in 32-bit kernels for entries from vm86 mode. This will OOPS both old kernels due to a bug and and 4.1-rc5 due to a regression I introduced, and it should make sure that the SYSENTER-from-vm86-mode hack in the kernel keeps working. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Jan Beulich <JBeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/09a9916761e0a9e42d4922f147af45a0079cc1e8.1432936374.git.luto@kernel.org Tests: 394838c96013 x86/asm/entry/32: Fix user_mode() misuses Tests: 7ba554b5ac69 x86/asm/entry/32: Really make user_mode() work correctly for VM86 mode Signed-off-by: Ingo Molnar <mingo@kernel.org>