65973dd3fd
i386 glibc is buggy and calls the sigaction syscall incorrectly. This is asymptomatic for normal programs, but it blows up on programs that do evil things with segmentation. The ldt_gdt self-test is an example of such an evil program. This doesn't appear to be a regression -- I think I just got lucky with the uninitialized memory that glibc threw at the kernel when I wrote the test. This hackish fix manually issues sigaction(2) syscalls to undo the damage. Without the fix, ldt_gdt_32 segfaults; with the fix, it passes for me. See: https://sourceware.org/bugzilla/show_bug.cgi?id=21269 Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> 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: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Garnier <thgarnie@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/aaab0f9f93c9af25396f01232608c163a760a668.1490218061.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>