[PATCH] perf/x86/intel/uncore: Avoid null dereferences (uncore_extra_pci_dev)

From: Steve Wahl <steve.wahl@hpe.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	Steve Wahl <steve.wahl@hpe.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] perf/x86/intel/uncore: Avoid null dereferences (uncore_extra_pci_dev)
Date: Thu, 15 Apr 2021 15:37:20 -0500	[thread overview]
Message-ID: <20210415203720.334007-1-steve.wahl@hpe.com> (raw)

If an uncore has no pci_init routine, or that routine fails,
uncore_pci_init is not called, and memory is not allocated for
uncore_extra_pci_dev.

So check to make sure uncore_extra_pci_dev is not NULL before use.

And fix the case that led us to discover the null derefs; don't fail
snbep_pci2phy_map_init if BIOS doesn't supply pcibus_to_node
information.

Fixes: 9a7832ce3d92 ("perf/x86/intel/uncore: With > 8 nodes, get pci bus die id from NUMA info")

Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
---
 arch/x86/events/intel/uncore_snbep.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index b79951d0707c..14c24356a2fa 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -1373,11 +1373,11 @@ static int snbep_pci2phy_map_init(int devid, int nodeid_loc, int idmap_loc, bool
 		/*
 		 * The nodeid and idmap registers only contain enough
 		 * information to handle 8 nodes.  On systems with more
-		 * than 8 nodes, we need to rely on NUMA information,
+		 * than 8 nodes, if available we rely on NUMA information,
 		 * filled in from BIOS supplied information, to determine
 		 * the topology.
 		 */
-		if (nr_node_ids <= 8) {
+		if ((nr_node_ids <= 8) || (pcibus_to_node(ubox_dev->bus) == -1)) {
 			/* get the Node ID of the local register */
 			err = pci_read_config_dword(ubox_dev, nodeid_loc, &config);
 			if (err)
@@ -2865,7 +2865,9 @@ void hswep_uncore_cpu_init(void)
 		hswep_uncore_cbox.num_boxes = boot_cpu_data.x86_max_cores;
 
 	/* Detect 6-8 core systems with only two SBOXes */
-	if (uncore_extra_pci_dev[pkg].dev[HSWEP_PCI_PCU_3]) {
+	if (!uncore_extra_pci_dev)
+		hswep_uncore_sbox.num_boxes = 2;
+	else if (uncore_extra_pci_dev[pkg].dev[HSWEP_PCI_PCU_3]) {
 		u32 capid4;
 
 		pci_read_config_dword(uncore_extra_pci_dev[pkg].dev[HSWEP_PCI_PCU_3],
@@ -3243,6 +3245,8 @@ void bdx_uncore_cpu_init(void)
 	if (boot_cpu_data.x86_model == 86) {
 		uncore_msr_uncores[BDX_MSR_UNCORE_SBOX] = NULL;
 	/* Detect systems with no SBOXes */
+	} else if (!uncore_extra_pci_dev) {
+		bdx_msr_uncores[BDX_MSR_UNCORE_SBOX] = NULL;
 	} else if (uncore_extra_pci_dev[pkg].dev[HSWEP_PCI_PCU_3]) {
 		struct pci_dev *pdev;
 		u32 capid4;
-- 
2.26.2

