From a2ec905d1e160a33b2e210e45ad30445ef26ce0e Mon Sep 17 00:00:00 2001
From: Alain Michaud <alainm@chromium.org>
Date: Mon, 27 Jul 2020 20:48:55 +0000
Subject: [PATCH] Bluetooth: fix kernel oops in store_pending_adv_report
Git-commit: a2ec905d1e160a33b2e210e45ad30445ef26ce0e
Patch-mainline: v5.8
References: CVE-2020-24490 bsc#1177726
Fix kernel oops observed when an ext adv data is larger than 31 bytes.
This can be reproduced by setting up an advertiser with advertisement
larger than 31 bytes. The issue is not sensitive to the advertisement
content. In particular, this was reproduced with an advertisement of
229 bytes filled with 'A'. See stack trace below.
This is fixed by not catching ext_adv as legacy adv are only cached to
be able to concatenate a scanable adv with its scan response before
sending it up through mgmt.
With ext_adv, this is no longer necessary.
general protection fault: 0000 [#1] SMP PTI
CPU: 6 PID: 205 Comm: kworker/u17:0 Not tainted 5.4.0-37-generic #41-Ubuntu
Hardware name: Dell Inc. XPS 15 7590/0CF6RR, BIOS 1.7.0 05/11/2020
Workqueue: hci0 hci_rx_work [bluetooth]
RIP: 0010:hci_bdaddr_list_lookup+0x1e/0x40 [bluetooth]
Code: ff ff e9 26 ff ff ff 0f 1f 44 00 00 0f 1f 44 00 00 55 48 8b 07 48 89 e5 48 39 c7 75 0a eb 24 48 8b 00 48 39 f8 74 1c 44 8b 06 <44> 39 40 10 75 ef 44 0f b7 4e 04 66 44 39 48 14 75 e3 38 50 16 75
RSP: 0018:ffffbc6a40493c70 EFLAGS: 00010286
RAX: 4141414141414141 RBX: 000000000000001b RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9903e76c100f RDI: ffff9904289d4b28
RBP: ffffbc6a40493c70 R08: 0000000093570362 R09: 0000000000000000
R10: 0000000000000000 R11: ffff9904344eae38 R12: ffff9904289d4000
R13: 0000000000000000 R14: 00000000ffffffa3 R15: ffff9903e76c100f
FS: 0000000000000000(0000) GS:ffff990434580000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feed125a000 CR3: 00000001b860a003 CR4: 00000000003606e0
Call Trace:
process_adv_report+0x12e/0x560 [bluetooth]
hci_le_meta_evt+0x7b2/0xba0 [bluetooth]
hci_event_packet+0x1c29/0x2a90 [bluetooth]
hci_rx_work+0x19b/0x360 [bluetooth]
process_one_work+0x1eb/0x3b0
worker_thread+0x4d/0x400
kthread+0x104/0x140
Fixes: c215e9397b00 ("Bluetooth: Process extended ADV report event")
Reported-by: Andy Nguyen <theflow@google.com>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Signed-off-by: Alain Michaud <alainm@chromium.org>
Tested-by: Sonny Sasaka <sonnysasaka@chromium.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
net/bluetooth/hci_event.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index cfeaee347db3..af9d7f2ff8ba 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -1338,6 +1338,9 @@ static void store_pending_adv_report(struct hci_dev *hdev, bdaddr_t *bdaddr,
{
struct discovery_state *d = &hdev->discovery;
+ if (len > HCI_MAX_AD_LENGTH)
+ return;
+
bacpy(&d->last_adv_addr, bdaddr);
d->last_adv_addr_type = bdaddr_type;
d->last_adv_rssi = rssi;
@@ -5355,7 +5358,8 @@ static struct hci_conn *check_pending_le_conn(struct hci_dev *hdev,
static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
u8 bdaddr_type, bdaddr_t *direct_addr,
- u8 direct_addr_type, s8 rssi, u8 *data, u8 len)
+ u8 direct_addr_type, s8 rssi, u8 *data, u8 len,
+ bool ext_adv)
{
struct discovery_state *d = &hdev->discovery;
struct smp_irk *irk;
@@ -5377,6 +5381,11 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
return;
}
+ if (!ext_adv && len > HCI_MAX_AD_LENGTH) {
+ bt_dev_err_ratelimited(hdev, "legacy adv larger than 31 bytes");
+ return;
+ }
+
/* Find the end of the data in case the report contains padded zero
* bytes at the end causing an invalid length value.
*
@@ -5437,7 +5446,7 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
*/
conn = check_pending_le_conn(hdev, bdaddr, bdaddr_type, type,
direct_addr);
- if (conn && type == LE_ADV_IND) {
+ if (!ext_adv && conn && type == LE_ADV_IND && len <= HCI_MAX_AD_LENGTH) {
/* Store report for later inclusion by
* mgmt_device_connected
*/
@@ -5491,7 +5500,7 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
* event or send an immediate device found event if the data
* should not be stored for later.
*/
- if (!has_pending_adv_report(hdev)) {
+ if (!ext_adv && !has_pending_adv_report(hdev)) {
/* If the report will trigger a SCAN_REQ store it for
* later merging.
*/
@@ -5526,7 +5535,8 @@ static void process_adv_report(struct hci_dev *hdev, u8 type, bdaddr_t *bdaddr,
/* If the new report will trigger a SCAN_REQ store it for
* later merging.
*/
- if (type == LE_ADV_IND || type == LE_ADV_SCAN_IND) {
+ if (!ext_adv && (type == LE_ADV_IND ||
+ type == LE_ADV_SCAN_IND)) {
store_pending_adv_report(hdev, bdaddr, bdaddr_type,
rssi, flags, data, len);
return;
@@ -5566,7 +5576,7 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
rssi = ev->data[ev->length];
process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
ev->bdaddr_type, NULL, 0, rssi,
- ev->data, ev->length);
+ ev->data, ev->length, false);
} else {
bt_dev_err(hdev, "Dropping invalid advertising data");
}
@@ -5638,7 +5648,8 @@ static void hci_le_ext_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
if (legacy_evt_type != LE_ADV_INVALID) {
process_adv_report(hdev, legacy_evt_type, &ev->bdaddr,
ev->bdaddr_type, NULL, 0, ev->rssi,
- ev->data, ev->length);
+ ev->data, ev->length,
+ !(evt_type & LE_EXT_ADV_LEGACY_PDU));
}
ptr += sizeof(*ev) + ev->length;
@@ -5836,7 +5847,8 @@ static void hci_le_direct_adv_report_evt(struct hci_dev *hdev,
process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
ev->bdaddr_type, &ev->direct_addr,
- ev->direct_addr_type, ev->rssi, NULL, 0);
+ ev->direct_addr_type, ev->rssi, NULL, 0,
+ false);
ptr += sizeof(*ev);
}
--
2.16.4