The `in` variable is set to -1 in kwboot_terminal() if stdin is not a tty. In this case we should not look whether -1 is set in fd_set, for it can lead to a buffer overflow, which can be reproduced with echo "xyz" | ./tools/kwboot -t /dev/ttyUSB0
Signed-off-by: Marek Behún <marek.be...@nic.cz> --- tools/kwboot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/kwboot.c b/tools/kwboot.c index 7feeaa45a2..e6e99849a7 100644 --- a/tools/kwboot.c +++ b/tools/kwboot.c @@ -552,7 +552,7 @@ kwboot_terminal(int tty) break; } - if (FD_ISSET(in, &rfds)) { + if (in >= 0 && FD_ISSET(in, &rfds)) { rc = kwboot_term_pipe(in, tty, quit, &s); if (rc) break; -- 2.31.1