net/bluetooth/rfcomm/tty.c: use-after-free

net/bluetooth/rfcomm/tty.c: use-after-free

[Adrian Bunk]

Commit 8de0a15483b357d0f0b821330ec84d1660cadc4e added the following 
use-after-free in net/bluetooth/rfcomm/tty.c:

<--  snip  -->

...
static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
{
...
        if (IS_ERR(dev->tty_dev)) {
                list_del(&dev->list);
                kfree(dev);
                return PTR_ERR(dev->tty_dev);
        }
...

<--  snip  -->

Spotted by the Coverity checker.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: net/bluetooth/rfcomm/tty.c: use-after-free

[Marcel Holtmann]

[-- Attachment #1: Type: text/plain, Size: 637 bytes --]

Hi Adrian,

> Commit 8de0a15483b357d0f0b821330ec84d1660cadc4e added the following 
> use-after-free in net/bluetooth/rfcomm/tty.c:
> 
> <--  snip  -->
> 
> ...
> static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
> {
> ...
>         if (IS_ERR(dev->tty_dev)) {
>                 list_del(&dev->list);
>                 kfree(dev);
>                 return PTR_ERR(dev->tty_dev);
>         }
> ...
> 
> <--  snip  -->
> 
> Spotted by the Coverity checker.

really good catch. I fully overlooked that one. The attached patch
should fix it.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Regards

Marcel


[-- Attachment #2: patch --]
[-- Type: text/x-patch, Size: 646 bytes --]

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 23ba61a..22a8320 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -267,7 +267,7 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
 out:
 	write_unlock_bh(&rfcomm_dev_lock);
 
-	if (err) {
+	if (err < 0) {
 		kfree(dev);
 		return err;
 	}
@@ -275,9 +275,10 @@ out:
 	dev->tty_dev = tty_register_device(rfcomm_tty_driver, dev->id, NULL);
 
 	if (IS_ERR(dev->tty_dev)) {
+		err = PTR_ERR(dev->tty_dev);
 		list_del(&dev->list);
 		kfree(dev);
-		return PTR_ERR(dev->tty_dev);
+		return err;
 	}
 
 	return dev->id;

[-- Attachment #3: Type: text/plain, Size: 315 bytes --]

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[-- Attachment #4: Type: text/plain, Size: 164 bytes --]

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Re: net/bluetooth/rfcomm/tty.c: use-after-free

[David Miller]

From: Marcel Holtmann <marcel@holtmann.org>
Date: Mon, 23 Jul 2007 09:47:12 +0200

> Hi Adrian,
> 
> > Commit 8de0a15483b357d0f0b821330ec84d1660cadc4e added the following 
> > use-after-free in net/bluetooth/rfcomm/tty.c:
 ...
> > Spotted by the Coverity checker.
> 
> really good catch. I fully overlooked that one. The attached patch
> should fix it.
> 
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

Applied, thanks everyone.

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