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([240d:1a:c0d:9f00:fc9c:8ee9:e32c:2d9]) by smtp.gmail.com with ESMTPSA id jd10-20020a170903260a00b00185507b5ef8sm2009003plb.50.2022.11.05.12.04.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Nov 2022 12:04:53 -0700 (PDT) From: Shigeru Yoshida To: marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Shigeru Yoshida , syzbot+19a9f729f05272857487@syzkaller.appspotmail.com Subject: [PATCH] Bluetooth: Fix use-after-free read in hci_cmd_timeout() Date: Sun, 6 Nov 2022 04:04:46 +0900 Message-Id: <20221105190446.1324053-1-syoshida@redhat.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org syzbot reported use-after-free in hci_cmd_timeout() [1]. The scenario for the issue is as follows: Task Workqueue ---------------------------------------------------------------------- hci_dev_open_sync ... hci_dev_init_sync <- failed ... if (hdev->sent_cmd) kfree_skb(hdev->sent_cmd) hci_cmd_timeout ... if (hdev->sent_cmd) sent = hdev->sent_cmd->data ^^ UAF occurred hdev->sent_cmd = NULL When hci_dev_init_sync() failed, hci_dev_open_sync() frees hdev->send_cmd and set it to NULL. However, hci_cmd_timeout() can run just after freeing hdev->sent_cmd because hdev->cmd_timer is not canceled. This patch fixes the issue by canceling hdev->cmd_timer before freeing hdev->sent_cmd. Link: https://syzkaller.appspot.com/bug?id=cb23ebfc8f304f510fb717cb783fe8b496c7ffb1 [1] Reported-by: syzbot+19a9f729f05272857487@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida --- net/bluetooth/hci_sync.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index 76c3107c9f91..a011065220e4 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -4696,6 +4696,7 @@ int hci_dev_open_sync(struct hci_dev *hdev) hdev->flush(hdev); if (hdev->sent_cmd) { + cancel_delayed_work_sync(&hdev->cmd_timer); kfree_skb(hdev->sent_cmd); hdev->sent_cmd = NULL; }