Messages in this thread Patch in this message | | | From | Xiaotian Feng <> | Subject | [PATCH] x86: fpu xstate fix memory poison overwritten | Date | Thu, 12 Aug 2010 18:45:45 +0800 |
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fpu.state is allocated from task_xstate_cachep, the size of task_xstate_cachep is xstate_size. But fpu.state is an union struct, which size is bigger than xstate_size if cpu_has_xsave, so if we want to visit fpu.state->xsave, the memory we allocated for fpu.state is not enough.
This caused many poison/redzone overwritten alerts on task_xstate while using kvm.
[ 1899.399373] ============================================================================= [ 1899.399377] BUG task_xstate: Poison overwritten [ 1899.399378] ----------------------------------------------------------------------------- [ 1899.399379] [ 1899.399382] INFO: 0xffff88020aca2100-0xffff88020aca217f. First byte 0x0 instead of 0x6b [ 1899.399385] INFO: Slab 0xffffea000725c300 objects=23 used=12 fp=0xffff88020aca2100 flags=0x200000000040c1 [ 1899.399387] INFO: Object 0xffff88020aca2100 @offset=8448 fp=0xffff88020aca23c0
With this patch applied, the poison overwritten alert disappeared.
Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: Avi Kivity <avi@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> --- arch/x86/kernel/process.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index d401f1d..609bee5 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -59,7 +59,7 @@ void free_thread_info(struct thread_info *ti) void arch_task_cache_init(void) { task_xstate_cachep = - kmem_cache_create("task_xstate", xstate_size, + kmem_cache_create("task_xstate", sizeof(union thread_xstate), __alignof__(union thread_xstate), SLAB_PANIC | SLAB_NOTRACK, NULL); } -- 1.7.2.1
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