From fa2a79ce6aef5de35a4d50487da35deb6b634944 Mon Sep 17 00:00:00 2001 From: James Custer Date: Sun, 2 Nov 2014 12:16:39 -0600 Subject: [PATCH] x86: UV BAU: Avoid NULL pointer reference in ptc_seq_show In init_per_cpu(), when get_cpu_topology() fails, init_per_cpu_tunables() is not called afterwards. This means that bau_control->statp is NULL. If a user then reads /proc/sgi_uv/ptc_statistics ptc_seq_show() references a NULL pointer. Therefore, since uv_bau_init calls set_bau_off when init_per_cpu() fails, we add code that detects when the bau is off in ptc_seq_show() to avoid referencing a NULL pointer. Signed-off-by: James Custer Cc: Russ Anderson Link: http://lkml.kernel.org/r/1414952199-185319-2-git-send-email-jcuster@sgi.com Signed-off-by: Thomas Gleixner --- arch/x86/platform/uv/tlb_uv.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c index 3968d67d366b..570b1b14375b 100644 --- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -1384,6 +1384,10 @@ static int ptc_seq_show(struct seq_file *file, void *data) } if (cpu < num_possible_cpus() && cpu_online(cpu)) { bcp = &per_cpu(bau_control, cpu); + if (bcp->nobau) { + seq_printf(file, "cpu %d bau disabled\n", cpu); + return 0; + } stat = bcp->statp; /* source side statistics */ seq_printf(file, -- 2.20.1