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[146.115.88.66]) by smtp.gmail.com with ESMTPSA id i7sm2571560qtb.27.2020.08.05.11.10.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Aug 2020 11:10:31 -0700 (PDT) From: Peilin Ye To: Marcel Holtmann , Johan Hedberg Cc: Peilin Ye , "David S. Miller" , Jakub Kicinski , Greg Kroah-Hartman , linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org Subject: [Linux-kernel-mentees] [PATCH net] Bluetooth: Fix slab-out-of-bounds read in hci_le_direct_adv_report_evt() Date: Wed, 5 Aug 2020 14:09:02 -0400 Message-Id: <20200805180902.684024-1-yepeilin.cs@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org `num_reports` is not being properly checked. A malformed event packet with a large `num_reports` number makes hci_le_direct_adv_report_evt() read out of bounds. Fix it. Reported-and-tested-by: syzbot+24ebd650e20bd263ca01@syzkaller.appspotmail.com Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct Advertising Report events") Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01 Signed-off-by: Peilin Ye --- I moved the initialization of `ev` out of the loop and restructured the function a bit, since otherwise the check would look like: if (!num_reports || skb->len < num_reports * sizeof(struct hci_ev_le_direct_adv_info) + 1) return; Therefore I used the similar structure with hci_inquiry_result_evt() etc. hci_le_adv_report_evt() and hci_le_ext_adv_report_evt() also have the same issue with `num_reports`, but I'm not sure how to perform the check for them, since they use variable-length reports. Should we do something like this? (take hci_le_adv_report_evt() as example:) if (!num_reports || skb->len < num_reports * (sizeof(*ev) + HCI_MAX_AD_LENGTH + 1) + 1) return; Then how about hci_le_ext_adv_report_evt()? There is no such `HCI_MAX_AD_LENGTH` restrictions on `ev->length` for it, I assume? Would like to hear your opinion. Thank you! net/bluetooth/hci_event.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 4b7fc430793c..aec43ae488d1 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -5863,21 +5863,19 @@ static void hci_le_direct_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb) { u8 num_reports = skb->data[0]; - void *ptr = &skb->data[1]; + struct hci_ev_le_direct_adv_info *ev = (void *)&skb->data[1]; - hci_dev_lock(hdev); + if (!num_reports || skb->len < num_reports * sizeof(*ev) + 1) + return; - while (num_reports--) { - struct hci_ev_le_direct_adv_info *ev = ptr; + hci_dev_lock(hdev); + for (; num_reports; num_reports--, ev++) process_adv_report(hdev, ev->evt_type, &ev->bdaddr, ev->bdaddr_type, &ev->direct_addr, ev->direct_addr_type, ev->rssi, NULL, 0, false); - ptr += sizeof(*ev); - } - hci_dev_unlock(hdev); }