commit 75154f402ef18e459ff97ddece25656b6c2b329c
author Andi Kleen <ak@suse.de> Sat Jun 23 02:29:25 2007 +0200
committer Linus Torvalds <torvalds@woody.linux-foundation.org> Fri Jun 22 18:41:19 2007 -0700
tree 6757b77ee2c712c4b64f334ff8c5b1a41a64083b
parent e2f1f19272f8de0374ad297b9806f8b6509e0013

x86_64: Ignore compat mode SYSCALL when IA32_EMULATION is not defined

Previously a program could switch to a compat mode segment and then
execute SYSCALL and it would jump to an uninitialized MSR and crash
the kernel.

Instead supply a dummy target for this case.

Pointed out by Jan Beulich

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86_64/kernel/entry.S

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index fa984b5..a67f87b 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -1163,3 +1163,10 @@
 	ret
 	CFI_ENDPROC
 ENDPROC(call_softirq)
+
+KPROBE_ENTRY(ignore_sysret)
+	CFI_STARTPROC
+	mov $-ENOSYS,%eax
+	sysret
+	CFI_ENDPROC
+ENDPROC(ignore_sysret)