console: fix out-of-bounds read in dputc(/dev/*, ...)

Trying to output a single character via
	echo -a /dev/serial0-1
currently results in garbage output after the newline, because console.c's
fops_write discards the buffer length and passes the buffer to
(struct cdev)::puts which only handles NUL-terminated strings.

Fix this by amending (struct cdev)::puts with a new nbytes parameter,
which is correctly propagated. All this functions now return at most the
nbytes parameter they were passed in. This fixes __console_puts, which
used to count new lines twice in its return value.

Fixes: b4f55fcf35 ("console: expose consoles in devfs")
Cc: Bastian Krause <bst@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/console.h b/include/console.h
index 4062e5abf6..7afe59e93a 100644
--- a/include/console.h
+++ b/include/console.h
@@ -42,7 +42,7 @@ struct console_device {
 
 	int (*tstc)(struct console_device *cdev);
 	void (*putc)(struct console_device *cdev, char c);
-	int (*puts)(struct console_device *cdev, const char *s);
+	int (*puts)(struct console_device *cdev, const char *s, size_t nbytes);
 	int  (*getc)(struct console_device *cdev);
 	int (*setbrg)(struct console_device *cdev, int baudrate);
 	void (*flush)(struct console_device *cdev);