linux-kernel - [PATCH 6/7] staging: comedi: check command direction in poll() file operation

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]

Date:	Thu, 30 Oct 2014 12:42:31 +0000
From:	Ian Abbott <abbotti@....co.uk>
To:	<driverdev-devel@...uxdriverproject.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ian Abbott <abbotti@....co.uk>,
	H Hartley Sweeten <hartleys@...ionengravers.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 6/7] staging: comedi: check command direction in poll() file operation

`comedi_poll()` handles the poll() file operation for comedi devices.

If no asynchronous command has been set up on the current "read"
subdevice, it sets the `POLLIN` and `POLLRDNORM` bits in the return
value to indicate that the read() file operation would not block as it
would return an error.  Add a check so it also does that if the
asynchronous command has been set up in the "write" direction as that
also causes the read() file operation to return an error.

Similarly, if no asynchronous command has need set up on the current
"write" subdevice, it sets the `POLLOUT` and `POLLWRNORM` bits in the
return value to indicate that the write() file operation would not block
as it would return an error.  Add a check so it also does that if the
asynchronous command has been set up in the "read" direction as that
also causes the write() file operation to return an error.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
 drivers/staging/comedi/comedi_fops.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 6328965..d55f709 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2017,6 +2017,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
 	if (s && s->async) {
 		poll_wait(file, &s->async->wait_head, wait);
 		if (!s->busy || !comedi_is_subdevice_running(s) ||
+		    (s->async->cmd.flags & CMDF_WRITE) ||
 		    comedi_buf_read_n_available(s) > 0)
 			mask |= POLLIN | POLLRDNORM;
 	}
@@ -2028,6 +2029,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
 		poll_wait(file, &s->async->wait_head, wait);
 		comedi_buf_write_alloc(s, s->async->prealloc_bufsz);
 		if (!s->busy || !comedi_is_subdevice_running(s) ||
+		    !(s->async->cmd.flags & CMDF_WRITE) ||
 		    comedi_buf_write_n_allocated(s) >= bps)
 			mask |= POLLOUT | POLLWRNORM;
 	}
-- 
2.1.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/