4.19-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Thompson daniel.thompson@linaro.org
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@lina... 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(-)
--- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -315,11 +315,9 @@ 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;