From: Paul Fulghum <paulkf@microgate.com>
To: "linux-kernel@vger.kernel.org Mailing List"
<linux-kernel@vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Arnd Bergmann <arnd@arndb.de>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
syzbot <syzbot+c244af085a0159d22879@syzkaller.appspotmail.com>,
jslaby@suse.com, syzkaller-bugs@googlegroups.com
Subject: [PATCH] tty/n_hdlc: fix __might_sleep warning
Date: Tue, 1 Jan 2019 12:28:53 -0800 [thread overview]
Message-ID: <F23DE81F-C976-4AED-8990-84A6ADC1BF1F@microgate.com> (raw)
In-Reply-To: <62FAC6A3-AC41-44CD-8ABC-79F404BF8CB1@microgate.com>
Fix __might_sleep warning in tty/n_hdlc.c read due to copy_to_user call while current is TASK_INTERRUPTIBLE.
This is a false positive since the code path does not depend on current state remaining TASK_INTERRUPTIBLE.
The loop breaks out and sets TASK_RUNNING after calling copy_to_user.
This patch supresses the warning by setting TASK_RUNNING before calling copy_to_user.
[1] https://syzkaller.appspot.com/bug?id=17d5de7f1fcab794cb8c40032f893f52de899324
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Reported-by: syzbot <syzbot+c244af085a0159d22879@syzkaller.appspotmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
—
--- a/drivers/tty/n_hdlc.c 2018-12-23 15:55:59.000000000 -0800
+++ b/drivers/tty/n_hdlc.c 2019-01-01 11:44:47.148153954 -0800
@@ -597,6 +597,7 @@ static ssize_t n_hdlc_tty_read(struct tt
/* too large for caller's buffer */
ret = -EOVERFLOW;
} else {
+ __set_current_state(TASK_RUNNING);
if (copy_to_user(buf, rbuf->buf, rbuf->count))
ret = -EFAULT;
else
next prev parent reply other threads:[~2019-01-01 20:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-29 0:41 WARNING in __might_sleep (2) syzbot
2018-12-29 11:48 ` [PATCH] tty/n_hdlc: fix sleep in !TASK_RUNNING state warning Tetsuo Handa
2019-01-01 3:13 ` Paul Fulghum
2019-01-01 20:28 ` Paul Fulghum [this message]
2019-01-10 11:38 ` [PATCH] tty/n_hdlc: fix __might_sleep warning Tetsuo Handa
2019-01-10 12:25 ` Arnd Bergmann
[not found] ` <FEBFE826-8D27-4A0B-86A5-BA559921CADC@microgate.com>
2019-01-02 15:04 ` [PATCH] tty/n_hdlc: fix sleep in !TASK_RUNNING state warning Tetsuo Handa
2019-01-02 20:55 ` Paul Fulghum
2019-01-03 9:09 ` Jiri Slaby
2019-01-03 11:32 ` Tetsuo Handa
2019-01-03 15:57 ` Paul Fulghum
2019-01-04 10:23 ` Tetsuo Handa
2019-01-04 13:57 ` Paul Fulghum
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