iscsi-target: Convert chap_server_compute_md5 to use kstrtoul

This patch converts chap_server_compute_md5() from simple_strtoul() to
kstrtoul usage().

This addresses the case where a empty 'CHAP_I=' key value received during
mutual authentication would be converted to a '0' by simple_strtoul(),
instead of failing the login attempt.

Reported-by: Tejas Vaykole <tejas.vaykole@calsoftinc.com>
Tested-by: Tejas Vaykole <tejas.vaykole@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/target/iscsi/iscsi_target_auth.c b/drivers/target/iscsi/iscsi_target_auth.c
index 19b842c3e0b3..9430eea7c0d6 100644
--- a/drivers/target/iscsi/iscsi_target_auth.c
+++ b/drivers/target/iscsi/iscsi_target_auth.c
@@ -174,7 +174,6 @@ static int chap_server_compute_md5(
         char *nr_out_ptr,
         unsigned int *nr_out_len)
 {
-        char *endptr;
         unsigned long id;
         unsigned char id_as_uchar;
         unsigned char digest[MD5_SIGNATURE_SIZE];
@@ -320,9 +319,14 @@ static int chap_server_compute_md5(
         }
 
         if (type == HEX)
-                id = simple_strtoul(&identifier[2], &endptr, 0);
+                ret = kstrtoul(&identifier[2], 0, &id);
         else
-                id = simple_strtoul(identifier, &endptr, 0);
+                ret = kstrtoul(identifier, 0, &id);
+
+        if (ret < 0) {
+                pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
+                goto out;
+        }
         if (id > 255) {
                 pr_err("chap identifier: %lu greater than 255\n", id);
                 goto out;