kdb: fix crash when KDB_BASE_CMD_MAX is exceeded

When the number of dyanmic kdb commands exceeds KDB_BASE_CMD_MAX, the
kernel will fault.

Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 3ab3feee7840..a6e729766821 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -82,7 +82,7 @@ static kdbtab_t kdb_base_commands[50];
 #define for_each_kdbcmd(cmd, num)                                       \
         for ((cmd) = kdb_base_commands, (num) = 0;                      \
              num < kdb_max_commands;                                    \
-             num == KDB_BASE_CMD_MAX ? cmd = kdb_commands : cmd++, num++)
+             num++, num == KDB_BASE_CMD_MAX ? cmd = kdb_commands : cmd++)
 
 typedef struct _kdbmsg {
         int     km_diag;        /* kdb diagnostic */
@@ -646,7 +646,7 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
         }
         if (!s->usable)
                 return KDB_NOTIMP;
-        s->command = kmalloc((s->count + 1) * sizeof(*(s->command)), GFP_KDB);
+        s->command = kzalloc((s->count + 1) * sizeof(*(s->command)), GFP_KDB);
         if (!s->command) {
                 kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
                            cmdstr);
@@ -2740,13 +2740,13 @@ int kdb_register_repeat(char *cmd,
                 }
                 if (kdb_commands) {
                         memcpy(new, kdb_commands,
-                               kdb_max_commands * sizeof(*new));
+                          (kdb_max_commands - KDB_BASE_CMD_MAX) * sizeof(*new));
                         kfree(kdb_commands);
                 }
                 memset(new + kdb_max_commands, 0,
                        kdb_command_extend * sizeof(*new));
                 kdb_commands = new;
-                kp = kdb_commands + kdb_max_commands;
+                kp = kdb_commands + kdb_max_commands - KDB_BASE_CMD_MAX;
                 kdb_max_commands += kdb_command_extend;
         }