This is a note to let you know that I've just added the patch titled
staging: comedi: check s->async for poll(), read() and write()
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
staging-comedi-check-s-async-for-poll-read-and-write.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From abbotti@xxxxxxxxx Fri Mar 1 11:20:18 2013
From: Ian Abbott <abbotti@xxxxxxxxx>
Date: Wed, 27 Feb 2013 10:56:19 +0000
Subject: staging: comedi: check s->async for poll(), read() and write()
To: stable@xxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxx, Ian Abbott <abbotti@xxxxxxxxx>
Message-ID: <1361962579-4790-1-git-send-email-abbotti@xxxxxxxxx>
From: Ian Abbott <abbotti@xxxxxxxxx>
commit cc400e185c07c15a42d2635995f422de5b94b696 upstream.
Some low-level comedi drivers (incorrectly) point `dev->read_subdev` or
`dev->write_subdev` to a subdevice that does not support asynchronous
commands. Comedi's poll(), read() and write() file operation handlers
assume these subdevices do support asynchronous commands. In
particular, they assume `s->async` is valid (where `s` points to the
read or write subdevice), which it won't be if it has been set
incorrectly. This can lead to a NULL pointer dereference.
Check `s->async` is non-NULL in `comedi_poll()`, `comedi_read()` and
`comedi_write()` to avoid the bug.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/comedi_fops.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1577,7 +1577,7 @@ static unsigned int comedi_poll(struct f
mask = 0;
read_subdev = comedi_get_read_subdevice(dev_file_info);
- if (read_subdev) {
+ if (read_subdev && read_subdev->async) {
poll_wait(file, &read_subdev->async->wait_head, wait);
if (!read_subdev->busy
|| comedi_buf_read_n_available(read_subdev->async) > 0
@@ -1587,7 +1587,7 @@ static unsigned int comedi_poll(struct f
}
}
write_subdev = comedi_get_write_subdevice(dev_file_info);
- if (write_subdev) {
+ if (write_subdev && write_subdev->async) {
poll_wait(file, &write_subdev->async->wait_head, wait);
comedi_buf_write_alloc(write_subdev->async,
write_subdev->async->prealloc_bufsz);
@@ -1629,7 +1629,7 @@ static ssize_t comedi_write(struct file
}
s = comedi_get_write_subdevice(dev_file_info);
- if (s == NULL) {
+ if (s == NULL || s->async == NULL) {
retval = -EIO;
goto done;
}
@@ -1740,7 +1740,7 @@ static ssize_t comedi_read(struct file *
}
s = comedi_get_read_subdevice(dev_file_info);
- if (s == NULL) {
+ if (s == NULL || s->async == NULL) {
retval = -EIO;
goto done;
}
Patches currently in stable-queue which might be from abbotti@xxxxxxxxx are
queue-3.4/staging-comedi-ni_labpc-set-up-command4-register-after-command3.patch
queue-3.4/staging-comedi-ni_labpc-correct-differential-channel-sequence-for-ai-commands.patch
queue-3.4/staging-comedi-check-s-async-for-poll-read-and-write.patch
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