powerpc/papr_scm: Fix leaking nvdimm_events_map elements

Right now 'char *' elements allocated for individual 'stat_id' in
'papr_scm_priv.nvdimm_events_map[]' during papr_scm_pmu_check_events(), get
leaked 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.

Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220511082637.646714-1-vaibhav@linux.ibm.com

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 39962c9..181b855 100644 (file)
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -125,8 +125,8 @@ struct papr_scm_priv {
        /* The bits which needs to be overridden */
        u64 health_bitmap_inject_mask;
 
-        /* array to have event_code and stat_id mappings */
-       char **nvdimm_events_map;
+       /* array to have event_code and stat_id mappings */
+       u8 *nvdimm_events_map;
 };
 
 static int papr_scm_pmem_flush(struct nd_region *nd_region,
@@ -370,7 +370,7 @@ static int papr_scm_pmu_get_value(struct perf_event *event, struct device *dev,
 
        stat = &stats->scm_statistic[0];
        memcpy(&stat->stat_id,
-              p->nvdimm_events_map[event->attr.config],
+              &p->nvdimm_events_map[event->attr.config * sizeof(stat->stat_id)],
                sizeof(stat->stat_id));
        stat->stat_val = 0;
 
@@ -462,14 +462,13 @@ 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;
        u32 available_events;
-
-       if (!p->stat_buffer_len)
-               return -ENOENT;
+       int index, rc = 0;
 
        available_events = (p->stat_buffer_len  - sizeof(struct papr_scm_perf_stats))
                        / sizeof(struct papr_scm_perf_stat);
+       if (available_events == 0)
+               return -EOPNOTSUPP;
 
        /* Allocate the buffer for phyp where stats are written */
        stats = kzalloc(p->stat_buffer_len, GFP_KERNEL);
@@ -478,35 +477,30 @@ 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->stat_id),
+                                      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 * sizeof(stat->stat_id)],
+                      &stat->stat_id, sizeof(stat->stat_id));
+       }
+out:
        kfree(stats);
        return rc;
 }