| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.12 068/118] x86/UV: Fix NULL pointer dereference in uv_flush_tlb_others() if the nobau boot option is used | Date | Wed, 18 Dec 2013 13:11:45 -0800 |
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3.12-stable review patch. If anyone has any objections, please let me know.
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From: cpw <cpw@sgi.com>
commit 3eae49ca8954f958b2001ab5643ef302cb7b67c7 upstream.
The SGI UV tlb shootdown code panics the system with a NULL pointer deference if 'nobau' is specified on the boot commandline.
uv_flush_tlb_other() gets called for every flush, whether the BAU is disabled or not. It should not be keeping the s_enters statistic while the BAU is disabled.
The panic occurs because during initialization init_per_cpu_tunables() does not set the bcp->statp pointer if 'nobau' was specified.
Signed-off-by: Cliff Wickman <cpw@sgi.com> Link: http://lkml.kernel.org/r/E1VnzBi-0005yF-MU@eag09.americas.sgi.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/platform/uv/tlb_uv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -1070,12 +1070,13 @@ const struct cpumask *uv_flush_tlb_other unsigned long status; bcp = &per_cpu(bau_control, cpu); - stat = bcp->statp; - stat->s_enters++; if (bcp->nobau) return cpumask; + stat = bcp->statp; + stat->s_enters++; + if (bcp->busy) { descriptor_status = read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_0);
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