kdb: Fix a potential buffer overflow in kdb_local()

When appending "[defcmd]" to 'kdb_prompt_str', the size of the string
already in the buffer should be taken into account.

An option could be to switch from strncat() to strlcat() which does the
correct test to avoid such an overflow.

However, this actually looks as dead code, because 'defcmd_in_progress'
can't be true here.
See a more detailed explanation at [1].

[1]: https://lore.kernel.org/all/CAD=FV=WSh7wKN7Yp-3wWiDgX4E3isQ8uh0LCzTmd1v9Cg9j+nQ@mail.gmail.com/

Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
This commit is contained in:
Christophe JAILLET 2023-11-25 13:05:04 +01:00 committed by Daniel Thompson
parent 610a9b8f49
commit 4f41d30cd6

View File

@ -1348,8 +1348,6 @@ do_full_getstr:
/* PROMPT can only be set if we have MEM_READ permission. */
snprintf(kdb_prompt_str, CMD_BUFLEN, kdbgetenv("PROMPT"),
raw_smp_processor_id());
if (defcmd_in_progress)
strncat(kdb_prompt_str, "[defcmd]", CMD_BUFLEN);
/*
* Fetch command from keyboard