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From: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Cc: Anant Thazhemadam <anant.thazhemadam@gmail.com>,
	syzbot+6ce141c55b2f7aafd1c4@syzkaller.appspotmail.com,
	Johan Hedberg <johan.hedberg@gmail.com>,
	linux-bluetooth@vger.kernel.org,
	Marcel Holtmann <marcel@holtmann.org>,
	linux-kernel@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH v3] bluetooth: hci_h5: fix memory leak in h5_close
Date: Sun,  4 Oct 2020 10:47:08 +0530	[thread overview]
Message-ID: <20201004051708.21985-1-anant.thazhemadam@gmail.com> (raw)
In-Reply-To: <20201001194329.9328-1-anant.thazhemadam@gmail.com>

When h5_close() is called and !hu->serdev, h5 is directly freed.
However, h5->rx_skb is not freed before h5 is freed, which causes
a memory leak.
Freeing h5->rx_skb (when !hu->serdev) fixes this memory leak before
freeing h5.

Fixes: ce945552fde4 ("Bluetooth: hci_h5: Add support for serdev enumerated devices")
Reported-by: syzbot+6ce141c55b2f7aafd1c4@syzkaller.appspotmail.com
Tested-by: syzbot+6ce141c55b2f7aafd1c4@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
---
Changes in v3:
	* Free h5->rx_skb when !hu->serdev, and fix the memory leak
	* Do not incorrectly and unnecessarily call serdev_device_close()

Changes in v2:
	* Fixed the Fixes tag

Hans de Goede also suggested calling h5_reset_rx() on close (for both, !hu->serdev
and hu->serdev cases). 
However, doing so seems to lead to a null-ptr-dereference error,
        https://syzkaller.appspot.com/text?tag=CrashReport&x=136a9a5d900000,
and for this reason, it has not been implemented.

Instead, directly freeing h5->rx_skb seems to suffice in preventing the memory leak
reported. 
And since h5 is freed immediately after freeing h5->rx_skb, assigning h5->rx_skb to
be NULL isn't necessary.

 drivers/bluetooth/hci_h5.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index e41854e0d79a..171e55c080ce 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -248,8 +248,10 @@ static int h5_close(struct hci_uart *hu)
 	if (h5->vnd && h5->vnd->close)
 		h5->vnd->close(h5);
 
-	if (!hu->serdev)
+	if (!hu->serdev){
+		kfree_skb(h5->rx_skb);
 		kfree(h5);
+	}
 
 	return 0;
 }
-- 
2.25.1

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  parent reply	other threads:[~2020-10-04  5:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 19:43 [Linux-kernel-mentees] [PATCH v2] bluetooth: hci_h5: close serdev device and free hu in h5_close Anant Thazhemadam
2020-10-02 10:22 ` Hans de Goede
2020-10-02 10:55   ` Anant Thazhemadam
2020-10-03 22:07   ` Anant Thazhemadam
2020-10-04  5:17 ` Anant Thazhemadam [this message]
2020-10-05  9:18   ` [Linux-kernel-mentees] [PATCH v3] bluetooth: hci_h5: fix memory leak " Hans de Goede
2020-10-06  2:44     ` Anant Thazhemadam
2020-10-06  6:30       ` Hans de Goede

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