diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2010-04-23 16:17:40 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2010-04-23 16:49:51 -0700 |
| commit | 7ce5a2b9bb2e92902230e3121d8c3047fab9cb47 (patch) | |
| tree | e8741ea11f5644d4a49ef9e4b66820977d577d3f | |
| parent | ae7c9b70dcb4313ea3dbcc9a2f240dae6c2b50c0 (diff) | |
x86-64: Clear a 64-bit FS/GS base on fork if selector is nonzero
When we do a thread switch, we clear the outgoing FS/GS base if the
corresponding selector is nonzero. This is taken by __switch_to() as
an entry invariant; it does not verify that it is true on entry.
However, copy_thread() doesn't enforce this constraint, which can
result in inconsistent results after fork().
Make copy_thread() match the behavior of __switch_to().
Reported-and-tested-by: Samuel Thibault <samuel.thibault@inria.fr>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <4BD1E061.8030605@zytor.com>
Cc: <stable@kernel.org>
| -rw-r--r-- | arch/x86/kernel/process_64.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index dc9690b4c4c..17cb3295cbf 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -276,12 +276,12 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, set_tsk_thread_flag(p, TIF_FORK); - p->thread.fs = me->thread.fs; - p->thread.gs = me->thread.gs; p->thread.io_bitmap_ptr = NULL; savesegment(gs, p->thread.gsindex); + p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs; savesegment(fs, p->thread.fsindex); + p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs; savesegment(es, p->thread.es); savesegment(ds, p->thread.ds); |