linux-kernel - [PATCH 4.4 044/113] serial: cpm_uart: return immediately from console poll

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181008175533.058054239@linuxfoundation.org>
Date:   Mon,  8 Oct 2018 20:30:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jason Wessel <jason.wessel@...driver.com>,
        Christophe Leroy <christophe.leroy@....fr>
Subject: [PATCH 4.4 044/113] serial: cpm_uart: return immediately from console poll

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Leroy <christophe.leroy@....fr>

commit be28c1e3ca29887e207f0cbcd294cefe5074bab6 upstream.

kgdb expects poll function to return immediately and
returning NO_POLL_CHAR when no character is available.

Fixes: f5316b4aea024 ("kgdb,8250,pl011: Return immediately from console poll")
Cc: Jason Wessel <jason.wessel@...driver.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/serial/cpm_uart/cpm_uart_core.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1068,8 +1068,8 @@ static int poll_wait_key(char *obuf, str
 	/* Get the address of the host memory buffer.
 	 */
 	bdp = pinfo->rx_cur;
-	while (bdp->cbd_sc & BD_SC_EMPTY)
-		;
+	if (bdp->cbd_sc & BD_SC_EMPTY)
+		return NO_POLL_CHAR;
 
 	/* If the buffer address is in the CPM DPRAM, don't
 	 * convert it.
@@ -1104,7 +1104,11 @@ static int cpm_get_poll_char(struct uart
 		poll_chars = 0;
 	}
 	if (poll_chars <= 0) {
-		poll_chars = poll_wait_key(poll_buf, pinfo);
+		int ret = poll_wait_key(poll_buf, pinfo);
+
+		if (ret == NO_POLL_CHAR)
+			return ret;
+		poll_chars = ret;
 		pollp = poll_buf;
 	}
 	poll_chars--;