[PATCH] Bluetooth: fix use-after-free in accessing skb after sending it

[PATCH] Bluetooth: fix use-after-free in accessing skb after sending it

[Pauli Virtanen]

hci_send_cmd_sync first sends skb and then tries to clone it.  However,
the driver may have already freed the skb at that point.

Fix by cloning the sent_cmd cloned just above, instead of the original.

Log:
================================================================
BUG: KASAN: slab-use-after-free in __copy_skb_header+0x1a/0x240
...
Call Trace: ..
 __skb_clone+0x59/0x2c0
 hci_cmd_work+0x3b3/0x3d0 [bluetooth]
 process_one_work+0x459/0x900
...
Allocated by task 129: ...
 __alloc_skb+0x1ae/0x220
 __hci_cmd_sync_sk+0x44c/0x7a0 [bluetooth]
 __hci_cmd_sync_status+0x24/0xb0 [bluetooth]
 set_cig_params_sync+0x778/0x7d0 [bluetooth]
...
Freed by task 0: ...
 kmem_cache_free+0x157/0x3c0
 __usb_hcd_giveback_urb+0x11e/0x1e0
 usb_giveback_urb_bh+0x1ad/0x2a0
 tasklet_action_common.isra.0+0x259/0x4a0
 __do_softirq+0x15b/0x5a7
================================================================

Fixes: ea5391e7b256 ("Bluetooth: hci_sync: Fix overwriting request callback")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---
 net/bluetooth/hci_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 6ca4c0df9f9c..df3aa41e376d 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4217,7 +4217,7 @@ static void hci_send_cmd_sync(struct hci_dev *hdev, struct sk_buff *skb)
 	if (hci_req_status_pend(hdev) &&
 	    !hci_dev_test_and_set_flag(hdev, HCI_CMD_PENDING)) {
 		kfree_skb(hdev->req_skb);
-		hdev->req_skb = skb_clone(skb, GFP_KERNEL);
+		hdev->req_skb = skb_clone(hdev->sent_cmd, GFP_KERNEL);
 	}
 
 	atomic_dec(&hdev->cmd_cnt);
-- 
2.44.0

RE: Bluetooth: fix use-after-free in accessing skb after sending it

[bluez.test.bot]

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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=831811

---Test result---

Test Summary:
CheckPatch                    PASS      0.66 seconds
GitLint                       PASS      0.32 seconds
SubjectPrefix                 PASS      0.12 seconds
BuildKernel                   PASS      29.18 seconds
CheckAllWarning               PASS      32.28 seconds
CheckSparse                   PASS      37.65 seconds
CheckSmatch                   PASS      102.16 seconds
BuildKernel32                 PASS      28.12 seconds
TestRunnerSetup               PASS      516.85 seconds
TestRunner_l2cap-tester       PASS      20.46 seconds
TestRunner_iso-tester         PASS      33.64 seconds
TestRunner_bnep-tester        PASS      4.95 seconds
TestRunner_mgmt-tester        FAIL      117.46 seconds
TestRunner_rfcomm-tester      PASS      7.59 seconds
TestRunner_sco-tester         PASS      11.26 seconds
TestRunner_ioctl-tester       PASS      8.24 seconds
TestRunner_mesh-tester        PASS      6.15 seconds
TestRunner_smp-tester         PASS      7.01 seconds
TestRunner_userchan-tester    PASS      5.15 seconds
IncrementalBuild              PASS      27.37 seconds

Details
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 488 (99.2%), Failed: 2, Not Run: 2

Failed Test Cases
LL Privacy - Add Device 5 (2 Devices to RL)          Failed       0.177 seconds
LL Privacy - Remove Device 4 (Disable Adv)           Timed out    2.270 seconds


---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: fix use-after-free in accessing skb after sending it

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Sat,  2 Mar 2024 19:06:23 +0200 you wrote:
> hci_send_cmd_sync first sends skb and then tries to clone it.  However,
> the driver may have already freed the skb at that point.
> 
> Fix by cloning the sent_cmd cloned just above, instead of the original.
> 
> Log:
> ================================================================
> BUG: KASAN: slab-use-after-free in __copy_skb_header+0x1a/0x240
> ...
> Call Trace: ..
>  __skb_clone+0x59/0x2c0
>  hci_cmd_work+0x3b3/0x3d0 [bluetooth]
>  process_one_work+0x459/0x900
> ...
> Allocated by task 129: ...
>  __alloc_skb+0x1ae/0x220
>  __hci_cmd_sync_sk+0x44c/0x7a0 [bluetooth]
>  __hci_cmd_sync_status+0x24/0xb0 [bluetooth]
>  set_cig_params_sync+0x778/0x7d0 [bluetooth]
> ...
> Freed by task 0: ...
>  kmem_cache_free+0x157/0x3c0
>  __usb_hcd_giveback_urb+0x11e/0x1e0
>  usb_giveback_urb_bh+0x1ad/0x2a0
>  tasklet_action_common.isra.0+0x259/0x4a0
>  __do_softirq+0x15b/0x5a7
> ================================================================
> 
> [...]

Here is the summary with links:
  - Bluetooth: fix use-after-free in accessing skb after sending it
    https://git.kernel.org/bluetooth/bluetooth-next/c/d147be932692

You are awesome, thank you!
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