x86, vsyscall: Use better error message on bad pointers

At least some UML versions run into this and need
vsyscall=native for now.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Andrew Lutomirski <luto@mit.edu>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Link: http://lkml.kernel.org/r/20111009134725.GD4586@localhost.pp.htv.fi
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 18ae83dd1cd7379ad79d0f9755fd6a0f8f369995..4ab7e322e0e6fda83c2986105a6abab88b6460ea 100644 (file)
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -206,7 +206,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
                 * vsyscalls harder, generate SIGSEGV here as well.
                 */
                warn_bad_vsyscall(KERN_INFO, regs,
-                                 "vsyscall fault (exploit attempt?)");
+                                 "vsyscall fault (exploit attempt?) - if this is a legitimate program boot with vsyscall=native (read kernel-parameters.txt for the security implications)");
                goto sigsegv;
        }