[PATCH] powerpc/papr_scm: Fix leaking nvdimm_events_map elements

[Vaibhav Jain]

Right now 'char *' elements allocated individual 'stat_id' in
'papr_scm_priv.nvdimm_events_map' during papr_scm_pmu_check_events() leak in
papr_scm_remove() and papr_scm_pmu_register(), papr_scm_pmu_check_events() error
paths.

Also individual 'stat_id' arent NULL terminated 'char *' instead they are fixed
8-byte sized identifiers. However papr_scm_pmu_register() assumes it to be a
NULL terminated 'char *' and at other places it assumes it to be a
'papr_scm_perf_stat.stat_id' sized string which is 8-byes in size.

Fix this by allocating the memory for papr_scm_priv.nvdimm_events_map to also
include space for 'stat_id' entries. This is possible since number of available
events/stat_ids are known upfront. This saves some memory and one extra level of
indirection from 'nvdimm_events_map' to 'stat_id'. Also rest of the code
can continue to call 'kfree(papr_scm_priv.nvdimm_events_map)' without needing to
iterate over the array and free up individual elements.

Also introduce a new typedef called 'state_id_t' thats a 'u8[8]' and can be used
across papr_scm to deal with stat_ids.

Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
---
 arch/powerpc/platforms/pseries/papr_scm.c | 48 +++++++++++------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 39962c905542..f33a865ad5fb 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -70,8 +70,10 @@
 #define PAPR_SCM_PERF_STATS_VERSION 0x1
 
 /* Struct holding a single performance metric */
+typedef u8 stat_id_t[8];
+
 struct papr_scm_perf_stat {
-	u8 stat_id[8];
+	stat_id_t stat_id;
 	__be64 stat_val;
 } __packed;
 
@@ -126,7 +128,7 @@ struct papr_scm_priv {
 	u64 health_bitmap_inject_mask;
 
 	 /* array to have event_code and stat_id mappings */
-	char **nvdimm_events_map;
+	stat_id_t *nvdimm_events_map;
 };
 
 static int papr_scm_pmem_flush(struct nd_region *nd_region,
@@ -462,7 +464,7 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu
 {
 	struct papr_scm_perf_stat *stat;
 	struct papr_scm_perf_stats *stats;
-	int index, rc, count;
+	int index, rc = 0;
 	u32 available_events;
 
 	if (!p->stat_buffer_len)
@@ -478,35 +480,29 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu
 		return rc;
 	}
 
-	/* Allocate memory to nvdimm_event_map */
-	p->nvdimm_events_map = kcalloc(available_events, sizeof(char *), GFP_KERNEL);
-	if (!p->nvdimm_events_map) {
-		rc = -ENOMEM;
-		goto out_stats;
-	}
-
 	/* Called to get list of events supported */
 	rc = drc_pmem_query_stats(p, stats, 0);
 	if (rc)
-		goto out_nvdimm_events_map;
-
-	for (index = 0, stat = stats->scm_statistic, count = 0;
-		     index < available_events; index++, ++stat) {
-		p->nvdimm_events_map[count] = kmemdup_nul(stat->stat_id, 8, GFP_KERNEL);
-		if (!p->nvdimm_events_map[count]) {
-			rc = -ENOMEM;
-			goto out_nvdimm_events_map;
-		}
+		goto out;
 
-		count++;
+	/*
+	 * Allocate memory and populate nvdimm_event_map.
+	 * Allocate an extra element for NULL entry
+	 */
+	p->nvdimm_events_map = kcalloc(available_events + 1,
+				       sizeof(stat_id_t), GFP_KERNEL);
+	if (!p->nvdimm_events_map) {
+		rc = -ENOMEM;
+		goto out;
 	}
-	p->nvdimm_events_map[count] = NULL;
-	kfree(stats);
-	return 0;
 
-out_nvdimm_events_map:
-	kfree(p->nvdimm_events_map);
-out_stats:
+	/* Copy all stat_ids to event map */
+	for (index = 0, stat = stats->scm_statistic;
+	     index < available_events; index++, ++stat) {
+		memcpy(&p->nvdimm_events_map[index], &stat->stat_id,
+		       sizeof(stat_id_t));
+	}
+out:
 	kfree(stats);
 	return rc;
 }

base-commit: 348c71344111d7a48892e3e52264ff11956fc196
-- 
2.35.1