perf pmus: Fixes always false when compare duplicates aliases

In the previous loop, all the members in the aliases[j-1] have been freed
and set to NULL. But in this loop, the function pmu_alias_is_duplicate()
compares the aliases[j] with the aliases[j-1] that has already been
disposed, so the function will always return false and duplicate aliases
will never be discarded.

If we find duplicate aliases, it skips the zfree aliases[j], which is
accompanied by a memory leak.

We can use the next aliases[j+1] to theck for duplicate aliases to
fixes the aliases NULL pointer dereference, then goto zfree code snippet
to release it.

After patch testing:
 $ perf list --unit=hisi_sicl,cpa pmu

 uncore cpa:
   cpa_p0_rd_dat_32b
        [Number of read ops transmitted by the P0 port which size is 32 bytes.
         Unit: hisi_sicl,cpa]
   cpa_p0_rd_dat_64b
        [Number of read ops transmitted by the P0 port which size is 64 bytes.
         Unit: hisi_sicl,cpa]

Fixes: c3245d2093c1 ("perf pmu: Abstract alias/event struct")
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Cc: ravi.bangoria@amd.com
Cc: james.clark@arm.com
Cc: prime.zeng@hisilicon.com
Cc: cuigaosheng1@huawei.com
Cc: jonathan.cameron@huawei.com
Cc: linuxarm@huawei.com
Cc: yangyicong@huawei.com
Cc: robh@kernel.org
Cc: renyu.zj@linux.alibaba.com
Cc: kjain@linux.ibm.com
Cc: john.g.garry@oracle.com
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240614094318.11607-1-hejunhao3@huawei.com

diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index 63b9cf9ccfa71f4279e47c31f6c28bdce14cc627..3fcabfd8fca190bf3870b9f6fe5fbc2674b3ff4f 100644 (file)
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -488,8 +488,8 @@ void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *p
        qsort(aliases, len, sizeof(struct sevent), cmp_sevent);
        for (int j = 0; j < len; j++) {
                /* Skip duplicates */
-               if (j > 0 && pmu_alias_is_duplicate(&aliases[j], &aliases[j - 1]))
-                       continue;
+               if (j < len - 1 && pmu_alias_is_duplicate(&aliases[j], &aliases[j + 1]))
+                       goto free;
 
                print_cb->print_event(print_state,
                                aliases[j].pmu_name,
@@ -502,6 +502,7 @@ void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *p
                                aliases[j].desc,
                                aliases[j].long_desc,
                                aliases[j].encoding_desc);
+free:
                zfree(&aliases[j].name);
                zfree(&aliases[j].alias);
                zfree(&aliases[j].scale_unit);