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Message-ID: <20220818115026.2237893-1-vincent.whitchurch@axis.com>
Date: Thu, 18 Aug 2022 13:50:26 +0200
From: Vincent Whitchurch <vincent.whitchurch@...s.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>
CC: <kernel@...s.com>,
Vincent Whitchurch <vincent.whitchurch@...s.com>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH v2] tty: Fix lookahead_buf crash with serdev
Do not follow a NULL pointer if the tty_port_client_operations does not
implement the ->lookahead_buf() callback, which is the case with
serdev's ttyport.
Fixes: 6bb6fa6908ebd3 ("tty: Implement lookahead to process XON/XOFF timely")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
Notes:
v2: Move more stuff into if block.
drivers/tty/tty_buffer.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 9fdecc795b6b..5e287dedce01 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -470,7 +470,6 @@ static void lookahead_bufs(struct tty_port *port, struct tty_buffer *head)
while (head) {
struct tty_buffer *next;
- unsigned char *p, *f = NULL;
unsigned int count;
/*
@@ -489,11 +488,16 @@ static void lookahead_bufs(struct tty_port *port, struct tty_buffer *head)
continue;
}
- p = char_buf_ptr(head, head->lookahead);
- if (~head->flags & TTYB_NORMAL)
- f = flag_buf_ptr(head, head->lookahead);
+ if (port->client_ops->lookahead_buf) {
+ unsigned char *p, *f = NULL;
+
+ p = char_buf_ptr(head, head->lookahead);
+ if (~head->flags & TTYB_NORMAL)
+ f = flag_buf_ptr(head, head->lookahead);
+
+ port->client_ops->lookahead_buf(port, p, f, count);
+ }
- port->client_ops->lookahead_buf(port, p, f, count);
head->lookahead += count;
}
}
--
2.34.1
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