From: Colin King <colin.king@canonical.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] n_tty: check for negative and zero space return from tty_write_room
Date: Thu, 28 Mar 2019 17:10:05 +0000 [thread overview]
Message-ID: <20190328171005.5822-1-colin.king@canonical.com> (raw)
From: Colin Ian King <colin.king@canonical.com>
The return from tty_write_room could potentially be negative if
a tty write_room driver returns an error number (not that any seem
to do). Rather than just check for a zero return, also check for
a -ve return. This avoids the unsigned nr being set to a large unsigned
value on the assignment from variable space and can lead to overflowing
the buffer buf. Better to be safe than assume all write_room
implementations in tty drivers are going to do the right thing.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
drivers/tty/n_tty.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 9cdb0fa3c4bf..66630787fbf9 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -550,7 +550,7 @@ static ssize_t process_output_block(struct tty_struct *tty,
mutex_lock(&ldata->output_lock);
space = tty_write_room(tty);
- if (!space) {
+ if (space <= 0) {
mutex_unlock(&ldata->output_lock);
return 0;
}
--
2.20.1
next reply other threads:[~2019-03-28 17:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-28 17:10 Colin King [this message]
2019-03-28 19:46 ` [PATCH] n_tty: check for negative and zero space return from tty_write_room Mukesh Ojha
2019-03-29 7:43 ` Dan Carpenter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190328171005.5822-1-colin.king@canonical.com \
--to=colin.king@canonical.com \
--cc=gregkh@linuxfoundation.org \
--cc=jslaby@suse.com \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox