Commit 3eae49ca authored Dec 03, 2013 by cpw Committed by Ingo Molnar Dec 10, 2013

x86/UV: Fix NULL pointer dereference in uv_flush_tlb_others() if the 'nobau' boot option is used



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>
Cc: <stable@vger.kernel.org> # 3.12.x
Link: http://lkml.kernel.org/r/E1VnzBi-0005yF-MU@eag09.americas.sgi.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 8b3b005d

arch/x86/platform/uv/tlb_uv.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1070,12 +1070,13 @@ const struct cpumask uv_flush_tlb_others(const struct cpumask cpumask,
		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);

Admin message