Re: [PATCH] staging; lirc, zilog: put_ir_rx may free 'rx' which canlead to double free

[Jesper Juhl]

On Fri, 29 Jul 2011, Dan Carpenter wrote:

> On Thu, Jul 28, 2011 at 11:49:51PM +0200, Jesper Juhl wrote:
> > If calling put_ir_rx(rx, true); in
> > drivers/staging/lirc/lirc_zilog.c::ir_probe() returns true (1) then it
> > means that it has freed it's first argument. Subsequently jumping to
> > 'out_put_xx' will cause us to call put_ir_rx() once more since 'rx' is
> > not zero - leading to a double free.
> 
> It would be better to just remove the first call to put_ir_rx().
> 

Taking a second look... Yes, you are right, that would be just fine and a 
lot simpler. Thanks for reviewing.

Here's an updated patch.


From: Jesper Juhl <jj@xxxxxxxxxxxxx>
Subject: [PATCH] staging; lirc, zilog: put_ir_rx may free 'rx' which can lead to double free

If the call to put_ir_rx(rx, true); in
drivers/staging/lirc/lirc_zilog.c::ir_probe() returns true (1) then it
means that it has freed it's first argument. Subsequently jumping to
'out_put_xx' will cause us to call put_ir_rx() once more since 'rx' is
not zero - leading to a double free.
To fix this, simply remove the first call to put_ir_rx().

Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
---
 drivers/staging/lirc/lirc_zilog.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/lirc/lirc_zilog.c b/drivers/staging/lirc/lirc_zilog.c
index 0302d82..6be6f67 100644
--- a/drivers/staging/lirc/lirc_zilog.c
+++ b/drivers/staging/lirc/lirc_zilog.c
@@ -1577,7 +1577,6 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
 			put_ir_device(ir, true);
 			/* Failure exit, so put back rx ref from i2c_client */
 			i2c_set_clientdata(client, NULL);
-			put_ir_rx(rx, true);
 			ir->l.features &= ~LIRC_CAN_REC_LIRCCODE;
 			goto out_put_xx;
 		}
-- 
1.7.6

-- 
Jesper Juhl <jj@xxxxxxxxxxxxx>       http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.

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