kdb: A fix for kdb command table expansion

When locally adding in some additional kdb commands, I stumbled
across an issue with the dynamic expansion of the kdb command table.
When the number of kdb commands exceeds the size of the statically
allocated kdb_base_commands[] array, additional space is allocated in
the kdb_register_repeat() routine.

The unused portion of the newly allocated array was not being initialized
to zero properly and this would result in segfaults when help '?' was
executed or when a search for a non-existing command would traverse the
command table beyond the end of valid command entries and then attempt
to use the non-zeroed area as actual command entries.

Signed-off-by: John Blackwood <john.blackwood@ccur.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 8875254120b66f9a0a6e784d83fc6a1e76f6f4c0..a52493a66cf29705d53be080663f8b15bd2ef556 100644 (file)
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -2739,7 +2739,7 @@ int kdb_register_repeat(char *cmd,
                          (kdb_max_commands - KDB_BASE_CMD_MAX) * sizeof(*new));
                        kfree(kdb_commands);
                }
-               memset(new + kdb_max_commands, 0,
+               memset(new + kdb_max_commands - KDB_BASE_CMD_MAX, 0,
                       kdb_command_extend * sizeof(*new));
                kdb_commands = new;
                kp = kdb_commands + kdb_max_commands - KDB_BASE_CMD_MAX;