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authorH. Peter Anvin <hpa@zytor.com>2010-04-23 16:17:40 -0700
committerH. Peter Anvin <hpa@zytor.com>2010-04-23 16:49:51 -0700
commit7ce5a2b9bb2e92902230e3121d8c3047fab9cb47 (patch)
treee8741ea11f5644d4a49ef9e4b66820977d577d3f /arch/x86/kernel
parentae7c9b70dcb4313ea3dbcc9a2f240dae6c2b50c0 (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>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/process_64.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index dc9690b4c4cc..17cb3295cbf7 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);