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>

1 files changed, 2 insertions, 8 deletions

diff --git a/arch/x86/ia32/ptrace32.c b/arch/x86/ia32/ptrace32.c
index f52770ef0ee3..4a233ad6269c 100644
--- a/arch/x86/ia32/ptrace32.c
+++ b/arch/x86/ia32/ptrace32.c
@@ -228,8 +228,6 @@ static long ptrace32_siginfo(unsigned request, u32 pid, u32 addr, u32 data)
         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 @@ asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
         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 @@ asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
         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);