perf script: Check session->header.env.arch before using it

stable inclusion
from stable-5.10.77
commit fbb91dadb512e8602c68ab6d5a049420aaebc55e
bugzilla: 185677 https://gitee.com/openeuler/kernel/issues/I4IAP7

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fbb91dadb512e8602c68ab6d5a049420aaebc55e

--------------------------------

commit 29c77550 upstream.

When perf.data is not written cleanly, we would like to process existing
data as much as possible (please see f_header.data.size == 0 condition
in perf_session__read_header). However, perf.data with partial data may
crash perf. Specifically, we see crash in 'perf script' for NULL
session->header.env.arch.

Fix this by checking session->header.env.arch before using it to determine
native_arch. Also split the if condition so it is easier to read.

Committer notes:

If it is a pipe, we already assume is a native arch, so no need to check
session->header.env.arch.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20211004053238.514936-1-songliubraving@fb.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

tools/perf/builtin-script.c

@@ -3820,11 +3820,15 @@ int cmd_script(int argc, const char **argv)
 		goto out_delete;
 
 	uname(&uts);
-	if (data.is_pipe ||  /* assume pipe_mode indicates native_arch */
-	    !strcmp(uts.machine, session->header.env.arch) ||
-	    (!strcmp(uts.machine, "x86_64") &&
-	     !strcmp(session->header.env.arch, "i386")))
+	if (data.is_pipe) { /* Assume pipe_mode indicates native_arch */
 		native_arch = true;
+	} else if (session->header.env.arch) {
+		if (!strcmp(uts.machine, session->header.env.arch))
+			native_arch = true;
+		else if (!strcmp(uts.machine, "x86_64") &&
+			 !strcmp(session->header.env.arch, "i386"))
+			native_arch = true;
+	}
 
 	script.session = session;
 	script__setup_sample_type(&script);