linux-kernel - [PATCH 3.11 28/36] staging: comedi: avoid memleak for subdevice private

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Message-Id: <20131126181030.987916707@linuxfoundation.org>
Date:	Tue, 26 Nov 2013 10:12:38 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Ian Abbott <abbotti@....co.uk>
Subject: [PATCH 3.11 28/36] staging: comedi: avoid memleak for subdevice private

3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ian Abbott <abbotti@....co.uk>

commit 67aa4acbc97f6a55b328e4e2305ef19cbe949d85 upstream.

`comedi_alloc_spriv()` allocates private storage for a comedi subdevice
and sets the `SRF_FREE_SPRIV` flag in the `runflags` member of the
subdevice to allow the private storage to be automatically freed when
the comedi device is being cleaned up.  Unfortunately, the flag gets
clobbered by `do_cmd_ioctl()` which calls
`comedi_set_subdevice_runflags()` with a mask value `~0` and only the
`SRF_USER` and `SRF_RUNNING` flags set, all the other SRF flags being
cleared.

Change the calls to `comedi_set_subdevice_runflags()` that currently use
a mask value of `~0` to use a more relevant mask value.  For
`do_cmd_ioctl()`, the relevant SRF flags are `SRF_USER`, `SRF_ERROR` and
`SRF_RUNNING`.  (At one time, `SRF_RT` would be included in that set of
flags, but it is no longer used.)  For `comedi_alloc_spriv()` replace
the call to `comedi_set_subdevice_runflags()` with a simple
OR-assignment to avoid unnecessary use of a spin-lock.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/staging/comedi/comedi_fops.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -543,7 +543,7 @@ void *comedi_alloc_spriv(struct comedi_s
 {
 	s->private = kzalloc(size, GFP_KERNEL);
 	if (s->private)
-		comedi_set_subdevice_runflags(s, ~0, SRF_FREE_SPRIV);
+		s->runflags |= SRF_FREE_SPRIV;
 	return s->private;
 }
 EXPORT_SYMBOL_GPL(comedi_alloc_spriv);
@@ -1485,7 +1485,8 @@ static int do_cmd_ioctl(struct comedi_de
 	if (async->cmd.flags & TRIG_WAKE_EOS)
 		async->cb_mask |= COMEDI_CB_EOS;

-	comedi_set_subdevice_runflags(s, ~0, SRF_USER | SRF_RUNNING);
+	comedi_set_subdevice_runflags(s, SRF_USER | SRF_ERROR | SRF_RUNNING,
+				      SRF_USER | SRF_RUNNING);

 	/* set s->busy _after_ setting SRF_RUNNING flag to avoid race with
 	 * comedi_read() or comedi_write() */

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