Fix use-after-free in get_plt_got_name().

Discovered using EXTRA_CFLAGS="-fsanitize=undefined -fsanitize=address".

Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/oe-lkp/202303061424.6ad43294-yujie.liu@intel.com
Fixes: ce4c8e7966f3 ("perf symbols: Get symbols for .plt.got for x86-64")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/util/symbol-elf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index c0a2de42c51b..7ef5f6d7d415 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -557,6 +557,7 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
 	const char *sym_name;
 	char *demangled;
 	GElf_Sym sym;
+	bool result;
 	u32 disp;
 
 	if (!di->sorted)
@@ -583,9 +584,11 @@ static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
 
 	snprintf(buf, buf_sz, "%s@plt", sym_name);
 
+	result = *sym_name;
+
 	free(demangled);
 
-	return *sym_name;
+	return result;
 }
 
 static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
-- 
2.34.1