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Commit 2467f3f1 authored by Daniel Thompson's avatar Daniel Thompson Committed by Greg Kroah-Hartman
Browse files

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: default avatarDouglas Anderson <dianders@chromium.org>
Tested-by: default avatarJustin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-5-f236dbe9828d@linaro.org


Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4a891827

kernel/debug/kdb/kdb_io.c

+3 −5
Original line number Diff line number Diff line
@@ -315,11 +315,9 @@ static char *kdb_read(char *buffer, size_t bufsize) 
		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;