* [PATCH] Bluetooth: hci_sync: Fix scan response data UAF
@ 2026-07-20 16:47 Chengfeng Ye
2026-07-20 18:55 ` bluez.test.bot
2026-07-20 19:54 ` [PATCH] " Luiz Augusto von Dentz
0 siblings, 2 replies; 3+ messages in thread
From: Chengfeng Ye @ 2026-07-20 16:47 UTC (permalink / raw)
To: Marcel Holtmann, Luiz Augusto von Dentz
Cc: linux-bluetooth, linux-kernel, Chengfeng Ye, stable
eir_create_scan_rsp() calls hci_find_adv_instance(), whose return value is
valid only while hdev->lock is held. After advertising setup was moved to
hci_cmd_sync_work, neither scan response data builder held that lock.
hci_set_ext_scan_rsp_data_sync() also kept the returned pointer while
waiting for the controller and wrote scan_rsp_changed through it afterward.
An advertising termination event can therefore interleave as follows:
hci_cmd_sync_work hci_rx_work
hci_find_adv_instance()
__hci_cmd_sync_status()
wait for controller reply hci_dev_lock()
hci_remove_adv_instance()
kfree(adv)
adv->scan_rsp_changed = false
KASAN reported:
BUG: KASAN: slab-use-after-free in hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
Write of size 1 at addr ffff88810a45d21d by task kworker/u17:0/88
Workqueue: hci0 hci_cmd_sync_work
Call Trace:
hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
hci_schedule_adv_instance_sync+0x390/0x4c0
hci_cmd_sync_work+0x173/0x300
Allocated by task 87:
hci_add_adv_instance+0x538/0xac0
add_advertising+0x885/0x1160
Freed by task 89:
kfree+0x131/0x3c0
hci_remove_adv_instance+0x1d8/0x3b0
hci_le_ext_adv_term_evt+0x17b/0x730
Hold hdev->lock while looking up the instance, building the scan
response, and clearing its dirty bit. Clear the bit before waiting for
the controller so no adv_info pointer survives the wait, and restore it
under the lock if the command fails. This also preserves an update that
races with a successful command because that update sets the bit again.
Protect the legacy scan response builder with the same lock.
Fixes: cba6b758711c ("Bluetooth: hci_sync: Make use of hci_cmd_sync_queue set 2")
Cc: stable@vger.kernel.org
Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
---
net/bluetooth/hci_sync.c | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 532534bc601c..8c69a98c71e8 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -1490,9 +1490,13 @@ static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
int err;
if (instance) {
+ hci_dev_lock(hdev);
+
adv = hci_find_adv_instance(hdev, instance);
- if (!adv || !adv->scan_rsp_changed)
+ if (!adv || !adv->scan_rsp_changed) {
+ hci_dev_unlock(hdev);
return 0;
+ }
}
len = eir_create_scan_rsp(hdev, instance, pdu->data);
@@ -1502,15 +1506,27 @@ static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
pdu->operation = LE_SET_ADV_DATA_OP_COMPLETE;
pdu->frag_pref = LE_SET_ADV_DATA_NO_FRAG;
+ if (adv) {
+ adv->scan_rsp_changed = false;
+ hci_dev_unlock(hdev);
+ }
+
err = __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_EXT_SCAN_RSP_DATA,
struct_size(pdu, data, len), pdu,
HCI_CMD_TIMEOUT);
- if (err)
+ if (err) {
+ if (instance) {
+ hci_dev_lock(hdev);
+ adv = hci_find_adv_instance(hdev, instance);
+ if (adv)
+ adv->scan_rsp_changed = true;
+ hci_dev_unlock(hdev);
+ }
+
return err;
+ }
- if (adv) {
- adv->scan_rsp_changed = false;
- } else {
+ if (!instance) {
memcpy(hdev->scan_rsp_data, pdu->data, len);
hdev->scan_rsp_data_len = len;
}
@@ -1525,8 +1541,14 @@ static int __hci_set_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
memset(&cp, 0, sizeof(cp));
+ if (instance)
+ hci_dev_lock(hdev);
+
len = eir_create_scan_rsp(hdev, instance, cp.data);
+ if (instance)
+ hci_dev_unlock(hdev);
+
if (hdev->scan_rsp_data_len == len &&
!memcmp(cp.data, hdev->scan_rsp_data, len))
return 0;
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: Bluetooth: hci_sync: Fix scan response data UAF
2026-07-20 16:47 [PATCH] Bluetooth: hci_sync: Fix scan response data UAF Chengfeng Ye
@ 2026-07-20 18:55 ` bluez.test.bot
2026-07-20 19:54 ` [PATCH] " Luiz Augusto von Dentz
1 sibling, 0 replies; 3+ messages in thread
From: bluez.test.bot @ 2026-07-20 18:55 UTC (permalink / raw)
To: linux-bluetooth, nicoyip.dev
[-- Attachment #1: Type: text/plain, Size: 2389 bytes --]
This is automated email and please do not reply to this email!
Dear submitter,
Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1131053
---Test result---
Test Summary:
CheckPatch PASS 0.76 seconds
VerifyFixes PASS 0.13 seconds
VerifySignedoff PASS 0.13 seconds
GitLint PASS 0.33 seconds
SubjectPrefix PASS 0.13 seconds
BuildKernel PASS 26.83 seconds
CheckAllWarning PASS 29.18 seconds
CheckSparse PASS 28.05 seconds
BuildKernel32 PASS 26.12 seconds
CheckKernelLLVM SKIP 0.00 seconds
TestRunnerSetup PASS 494.85 seconds
TestRunner_l2cap-tester PASS 59.19 seconds
TestRunner_iso-tester PASS 77.64 seconds
TestRunner_bnep-tester PASS 19.49 seconds
TestRunner_mgmt-tester FAIL 209.24 seconds
TestRunner_rfcomm-tester PASS 25.07 seconds
TestRunner_sco-tester PASS 31.10 seconds
TestRunner_ioctl-tester PASS 25.70 seconds
TestRunner_mesh-tester FAIL 26.02 seconds
TestRunner_smp-tester PASS 22.95 seconds
TestRunner_userchan-tester PASS 20.46 seconds
TestRunner_6lowpan-tester PASS 25.12 seconds
IncrementalBuild PASS 25.36 seconds
Details
##############################
Test: CheckKernelLLVM - SKIP
Desc: Build kernel with LLVM + context analysis
Output:
Clang not found
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4
Failed Test Cases
Read Exp Feature - Success Failed 0.236 seconds
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0
Failed Test Cases
Mesh - Send cancel - 1 Timed out 2.584 seconds
Mesh - Send cancel - 2 Timed out 1.989 seconds
https://github.com/bluez/bluetooth-next/pull/464
---
Regards,
Linux Bluetooth
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Bluetooth: hci_sync: Fix scan response data UAF
2026-07-20 16:47 [PATCH] Bluetooth: hci_sync: Fix scan response data UAF Chengfeng Ye
2026-07-20 18:55 ` bluez.test.bot
@ 2026-07-20 19:54 ` Luiz Augusto von Dentz
1 sibling, 0 replies; 3+ messages in thread
From: Luiz Augusto von Dentz @ 2026-07-20 19:54 UTC (permalink / raw)
To: Chengfeng Ye; +Cc: Marcel Holtmann, linux-bluetooth, linux-kernel, stable
Hi,
On Mon, Jul 20, 2026 at 12:47 PM Chengfeng Ye <nicoyip.dev@gmail.com> wrote:
>
> eir_create_scan_rsp() calls hci_find_adv_instance(), whose return value is
> valid only while hdev->lock is held. After advertising setup was moved to
> hci_cmd_sync_work, neither scan response data builder held that lock.
> hci_set_ext_scan_rsp_data_sync() also kept the returned pointer while
> waiting for the controller and wrote scan_rsp_changed through it afterward.
>
> An advertising termination event can therefore interleave as follows:
>
> hci_cmd_sync_work hci_rx_work
> hci_find_adv_instance()
> __hci_cmd_sync_status()
> wait for controller reply hci_dev_lock()
> hci_remove_adv_instance()
> kfree(adv)
> adv->scan_rsp_changed = false
>
> KASAN reported:
>
> BUG: KASAN: slab-use-after-free in hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
> Write of size 1 at addr ffff88810a45d21d by task kworker/u17:0/88
> Workqueue: hci0 hci_cmd_sync_work
> Call Trace:
> hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
> hci_schedule_adv_instance_sync+0x390/0x4c0
> hci_cmd_sync_work+0x173/0x300
> Allocated by task 87:
> hci_add_adv_instance+0x538/0xac0
> add_advertising+0x885/0x1160
> Freed by task 89:
> kfree+0x131/0x3c0
> hci_remove_adv_instance+0x1d8/0x3b0
> hci_le_ext_adv_term_evt+0x17b/0x730
>
> Hold hdev->lock while looking up the instance, building the scan
> response, and clearing its dirty bit. Clear the bit before waiting for
> the controller so no adv_info pointer survives the wait, and restore it
> under the lock if the command fails. This also preserves an update that
> races with a successful command because that update sets the bit again.
> Protect the legacy scan response builder with the same lock.
>
> Fixes: cba6b758711c ("Bluetooth: hci_sync: Make use of hci_cmd_sync_queue set 2")
> Cc: stable@vger.kernel.org
> Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
> ---
> net/bluetooth/hci_sync.c | 32 +++++++++++++++++++++++++++-----
> 1 file changed, 27 insertions(+), 5 deletions(-)
>
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index 532534bc601c..8c69a98c71e8 100644
> --- a/net/bluetooth/hci_sync.c
> +++ b/net/bluetooth/hci_sync.c
> @@ -1490,9 +1490,13 @@ static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
> int err;
>
> if (instance) {
> + hci_dev_lock(hdev);
> +
> adv = hci_find_adv_instance(hdev, instance);
> - if (!adv || !adv->scan_rsp_changed)
> + if (!adv || !adv->scan_rsp_changed) {
> + hci_dev_unlock(hdev);
> return 0;
> + }
> }
>
> len = eir_create_scan_rsp(hdev, instance, pdu->data);
> @@ -1502,15 +1506,27 @@ static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
> pdu->operation = LE_SET_ADV_DATA_OP_COMPLETE;
> pdu->frag_pref = LE_SET_ADV_DATA_NO_FRAG;
>
> + if (adv) {
> + adv->scan_rsp_changed = false;
> + hci_dev_unlock(hdev);
> + }
> +
> err = __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_EXT_SCAN_RSP_DATA,
> struct_size(pdu, data, len), pdu,
> HCI_CMD_TIMEOUT);
> - if (err)
> + if (err) {
> + if (instance) {
> + hci_dev_lock(hdev);
> + adv = hci_find_adv_instance(hdev, instance);
> + if (adv)
> + adv->scan_rsp_changed = true;
> + hci_dev_unlock(hdev);
> + }
> +
> return err;
> + }
>
> - if (adv) {
> - adv->scan_rsp_changed = false;
> - } else {
> + if (!instance) {
> memcpy(hdev->scan_rsp_data, pdu->data, len);
> hdev->scan_rsp_data_len = len;
> }
> @@ -1525,8 +1541,14 @@ static int __hci_set_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
>
> memset(&cp, 0, sizeof(cp));
>
> + if (instance)
> + hci_dev_lock(hdev);
> +
> len = eir_create_scan_rsp(hdev, instance, cp.data);
>
> + if (instance)
> + hci_dev_unlock(hdev);
> +
> if (hdev->scan_rsp_data_len == len &&
> !memcmp(cp.data, hdev->scan_rsp_data, len))
> return 0;
> --
> 2.43.0
It looks like Sashiko found some other places where this could be a problem:
https://sashiko.dev/#/patchset/20260720164738.2921802-1-nicoyip.dev%40gmail.com
--
Luiz Augusto von Dentz
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-07-20 16:47 [PATCH] Bluetooth: hci_sync: Fix scan response data UAF Chengfeng Ye
2026-07-20 18:55 ` bluez.test.bot
2026-07-20 19:54 ` [PATCH] " Luiz Augusto von Dentz
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