From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Cliff Wickman , Ingo Molnar 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 Message-Id: <20131218211221.380254523@linuxfoundation.org> In-Reply-To: <20131218211219.461663463@linuxfoundation.org> References: <20131218211219.461663463@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: cpw 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 Link: http://lkml.kernel.org/r/E1VnzBi-0005yF-MU@eag09.americas.sgi.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- 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);