[Crash-utility] [PATCH v2] Fixed the segment fault when ikconfig passed nonstandard values

[liuyun01 at tj.kylinos.cn]

From: Jackie Liu <liuyun01 at kylinos.cn>

Some strange reasons may cause kcore to collect some strange
entries of ikconfig, such as CONFIG_SECU+[some hex data] causes
the 'val' to be NULL, and then crashes when strdup.

CONFIG_SECU+[some hex data] to be **strings that don't
contain the delimitor string '='** and then strtok_r() interprets
it as consisting of a single token, hence val resulting in having NULL.

[d.hatayama at fujitsu.com: rewrite comment]
Suggested-by: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
Signed-off-by: Jackie Liu <liuyun01 at kylinos.cn>
---
 kernel.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/kernel.c b/kernel.c
index 9871637..c8182a6 100644
--- a/kernel.c
+++ b/kernel.c
@@ -10236,7 +10236,7 @@ static struct ikconfig_list {
 	char *val;
 } *ikconfig_all;
 
-static void add_ikconfig_entry(char *line, struct ikconfig_list *ent)
+static int add_ikconfig_entry(char *line, struct ikconfig_list *ent)
 {
 	char *tokptr, *name, *val;
 
@@ -10244,8 +10244,16 @@ static void add_ikconfig_entry(char *line, struct ikconfig_list *ent)
 	sscanf(name, "CONFIG_%s", name);
 	val = strtok_r(NULL, "", &tokptr);
 
+	if (!val) {
+		if (CRASHDEBUG(2))
+			error(WARNING, "invalid ikconfig entry: %s\n", line);
+		return FALSE;
+	}
+
 	ent->name = strdup(name);
 	ent->val = strdup(val);
+
+	return TRUE;
 }
 
 static int setup_ikconfig(char *config)
@@ -10265,8 +10273,8 @@ static int setup_ikconfig(char *config)
 			ent++;
 
 		if (STRNEQ(ent, "CONFIG_")) {
-			add_ikconfig_entry(ent,
-					 &ikconfig_all[kt->ikconfig_ents++]);
+			if (add_ikconfig_entry(ent, &ikconfig_all[kt->ikconfig_ents]))
+				kt->ikconfig_ents++;
 			if (kt->ikconfig_ents == IKCONFIG_MAX) {
 				error(WARNING, "ikconfig overflow.\n");
 				return 1;
-- 
2.17.1