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>

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 3ab3fee..a6e7297 100644 (file)
--- 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;
        }