[PATCH] x86_64: Don't allow accesses below register frame in ptrace
There was a "off by one quad word" error in there. I don't think it is
exploitable because it will only store into a unused area, but better to plug
it.
Found and fixed by John Blackwood
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index 60dc9b9..525f6a1 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -380,7 +380,7 @@
break;
switch (addr) {
- case 0 ... sizeof(struct user_regs_struct):
+ case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
tmp = getreg(child, addr);
break;
case offsetof(struct user, u_debugreg[0]):
@@ -425,7 +425,7 @@
break;
switch (addr) {
- case 0 ... sizeof(struct user_regs_struct):
+ case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
ret = putreg(child, addr, data);
break;
/* Disallows to set a breakpoint into the vsyscall */