Hi,
On Sat, Oct 28, 2023 at 6:55 AM Christophe JAILLET
<christophe.jaillet@xxxxxxxxxx> wrote:
>
> When appending "[defcmd]" to 'kdb_prompt_str', the size of the string
> already in the buffer should be taken into account.
>
> Switch from strncat() to strlcat() which does the correct test to avoid
> such an overflow.
>
> Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> ---
> kernel/debug/kdb/kdb_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> index 438b868cbfa9..e5f0bf0f45d1 100644
> --- a/kernel/debug/kdb/kdb_main.c
> +++ b/kernel/debug/kdb/kdb_main.c
> @@ -1350,7 +1350,7 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
> snprintf(kdb_prompt_str, CMD_BUFLEN, kdbgetenv("PROMPT"),
> raw_smp_processor_id());
> if (defcmd_in_progress)
> - strncat(kdb_prompt_str, "[defcmd]", CMD_BUFLEN);
> + strlcat(kdb_prompt_str, "[defcmd]", CMD_BUFLEN);
Some of this code is a bit hard to follow, but I think it's better to
simply delete the whole "strncat". Specifically, as of commit
a37372f6c3c0 ("kdb: Prevent kernel oops with kdb_defcmd") it's clear
that "defcmd" can't actually be run to define new commands
interactively. It's also clear to me that "defcmd_in_progress" is only
set when defining new commands.
The prompt being constructed here is a prompt that's printed to the
end user when working interactively. That means the "if
(defcmd_in_progress)" should never be true and it can be deleted as
dead code.
-Doug
