perf tools kvm: Fix the potential out of range memory access issue

kvm_add_default_arch_event() helper may add 2 extra options but it
directly modifies the original argv[] array. This may cause out of range
memory access. Fix this issue.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 9813f1eb56f9b29cc424562e897f27f897b25f3b..d297a7b2c088a6eb145ae0098f4d4beb91f53aa3 100644 (file)
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -2008,11 +2008,12 @@ static int __cmd_record(const char *file_name, int argc, const char **argv)
        int rec_argc, i = 0, j, ret;
        const char **rec_argv;
 
-       ret = kvm_add_default_arch_event(&argc, argv);
-       if (ret)
-               return -EINVAL;
-
-       rec_argc = argc + 2;
+       /*
+        * Besides the 2 more options "-o" and "filename",
+        * kvm_add_default_arch_event() may add 2 extra options,
+        * so allocate 4 more items.
+        */
+       rec_argc = argc + 2 + 2;
        rec_argv = calloc(rec_argc + 1, sizeof(char *));
        if (!rec_argv)
                return -ENOMEM;
@@ -2025,6 +2026,10 @@ static int __cmd_record(const char *file_name, int argc, const char **argv)
 
        BUG_ON(i != rec_argc);
 
+       ret = kvm_add_default_arch_event(&i, rec_argv);
+       if (ret)
+               goto EXIT;
+
        ret = cmd_record(i, rec_argv);
 
 EXIT: