From f76fd94ae697267e92316819569818fa56fc32c7 Mon Sep 17 00:00:00 2001
From: Daniel Thompson <daniel.thompson@linaro.org>
Date: Wed, 24 Apr 2024 15:03:38 +0100
Subject: [PATCH] kdb: Use format-specifiers rather than memset() for padding
in kdb_read()
commit c9b51ddb66b1d96e4d364c088da0f1dfb004c574 upstream.
Currently when the current line should be removed from the display
kdb_read() uses memset() to fill a temporary buffer with spaces.
The problem is not that this could be trivially implemented using a
format string rather than open coding it. The real problem is that
it is possible, on systems with a long kdb_prompt_str, to write past
the end of the tmpbuffer.
Happily, as mentioned above, this can be trivially implemented using a
format string. Make it so!
Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-5-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/debug/kdb/kdb_io.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 91872c42cd7e..a3b4b55d2e2e 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -305,11 +305,9 @@ poll_again:
break;
case 14: /* Down */
case 16: /* Up */
- memset(tmpbuffer, ' ',
- strlen(kdb_prompt_str) + (lastchar-buffer));
- *(tmpbuffer+strlen(kdb_prompt_str) +
- (lastchar-buffer)) = '\0';
- kdb_printf("\r%s\r", tmpbuffer);
+ kdb_printf("\r%*c\r",
+ (int)(strlen(kdb_prompt_str) + (lastchar - buffer)),
+ ' ');
*lastchar = (char)key;
*(lastchar+1) = '\0';
return lastchar;