commit 332e0e17ad49e084b7db670ef43b5eb59abd9e34 upstream.
comedi_open() invokes comedi_dev_get_from_minor(), which returns a
reference of the COMEDI device to "dev" with increased refcount.
When comedi_open() returns, "dev" becomes invalid, so the refcount
should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of
comedi_open(). When "cfp" allocation is failed, the refcnt increased by
comedi_dev_get_from_minor() is not decreased, causing a refcnt leak.
Fix this issue by calling comedi_dev_put() on this error path when "cfp"
allocation is failed.
Fixes: 20f083c07565 ("staging: comedi: prepare support for per-file read and write subdevices")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/1587361459-83622-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ed87d33ddbcd9a1c3b5ae87995da34e6f51a862c upstream.
The DT2815 analog output command is 16 bits wide, consisting of the
12-bit sample value in bits 15 to 4, the channel number in bits 3 to 1,
and a voltage or current selector in bit 0. Both bytes of the 16-bit
command need to be written in turn to a single 8-bit data register.
However, the driver currently only writes the low 8-bits. It is broken
and appears to have always been broken.
Electronic copies of the DT2815 User's Manual seem impossible to find
online, but looking at the source code, a best guess for the sequence
the driver intended to use to write the analog output command is as
follows:
1. Wait for the status register to read 0x00.
2. Write the low byte of the command to the data register.
3. Wait for the status register to read 0x80.
4. Write the high byte of the command to the data register.
Step 4 is missing from the driver. Add step 4 to (hopefully) fix the
driver.
Also add a "FIXME" comment about setting bit 0 of the low byte of the
command. Supposedly, it is used to choose between voltage output and
current output, but the current driver always sets it to 1.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200406142015.126982-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Xiyu Yang