x86_64: ia32 ptrace THREAD_AREA fix
The addr argument to PTRACE_GET_THREAD_AREA and PTRACE_SET_THREAD_AREA is
not a magic constant. It's derived from the segment register values being
used, which are computed originally from the index used with set_thread_area.
The value does not need to match what a native i386 kernel would accept.
It needs to match the segment selectors that can actually be in use in this
32-bit process. The 64-bit ptrace support for PTRACE_GET_THREAD_AREA
(normally used only on 32-bit processes) is correct, but the 32-bit emulation
of ptrace is broken.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/ia32/ptrace32.c b/arch/x86/ia32/ptrace32.c
index f52770e..4a233ad 100644
--- a/arch/x86/ia32/ptrace32.c
+++ b/arch/x86/ia32/ptrace32.c
@@ -228,8 +228,6 @@
return ret;
}
-#define COMPAT_GDT_ENTRY_TLS_MIN 6
-
asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
{
struct task_struct *child;
@@ -248,6 +246,8 @@
case PTRACE_SYSCALL:
case PTRACE_OLDSETOPTIONS:
case PTRACE_SETOPTIONS:
+ case PTRACE_SET_THREAD_AREA:
+ case PTRACE_GET_THREAD_AREA:
return sys_ptrace(request, pid, addr, data);
default:
@@ -271,12 +271,6 @@
case PTRACE_SETSIGINFO:
case PTRACE_GETSIGINFO:
return ptrace32_siginfo(request, pid, addr, data);
-
- case PTRACE_SET_THREAD_AREA:
- case PTRACE_GET_THREAD_AREA:
- return sys_ptrace(request, pid,
- addr + GDT_ENTRY_TLS_MIN - COMPAT_GDT_ENTRY_TLS_MIN,
- data);
}
child = ptrace_get_task_struct(pid);