soc: apple: rtkit: Cut syslog messages after the first '\0'

Certain messages from DCP contain NUL bytes in the random data after the
NUL terminated syslog message. Since the syslog message ends with '\n'
this results in a dev_info() message terminated with two newlines and an
empty printed line in the kernel log.

Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://lore.kernel.org/r/20250226-apple-soc-misc-v2-4-c3ec37f9021b@svenpeter.dev
Signed-off-by: Sven Peter <sven@svenpeter.dev>

diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
index 4b78463dd5a1002d2a8f54726729d2370b8dc560..5fffd0f003dc2f4f377faf96cce0c1ce4ff0b788 100644 (file)
--- a/drivers/soc/apple/rtkit.c
+++ b/drivers/soc/apple/rtkit.c
@@ -477,7 +477,7 @@ static void apple_rtkit_syslog_rx_log(struct apple_rtkit *rtk, u64 msg)
 
        log_context[sizeof(log_context) - 1] = 0;
 
-       msglen = rtk->syslog_msg_size - 1;
+       msglen = strnlen(rtk->syslog_msg_buffer, rtk->syslog_msg_size - 1);
        while (msglen > 0 &&
                   should_crop_syslog_char(rtk->syslog_msg_buffer[msglen - 1]))
                msglen--;