diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2010-04-23 16:17:40 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-12 14:57:06 -0700 |
| commit | e620234b3ec62cedcdc3a8c53ed50facd4392cb3 (patch) | |
| tree | 3fe16fa17d560d481b5857dced8628fa15b90f26 | |
| parent | 6dc36b37f62f666c802b184f01106fd222d36bd2 (diff) | |
x86-64: Clear a 64-bit FS/GS base on fork if selector is nonzero
commit 7ce5a2b9bb2e92902230e3121d8c3047fab9cb47 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86/kernel/process_64.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 6eabe9004126..868fdb407bb9 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -295,11 +295,10 @@ 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; - 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); |