[PATCH] Bluetooth: l2cap: Fix double free of 'skb'

[PATCH] Bluetooth: l2cap: Fix double free of 'skb'

[Frédéric Danis]

Commit ad5747d4eed1 ("Bluetooth: l2cap: Process valid commands in too
long frame") from Apr 14, 2025 (linux-next), leads to the following
Smatch static checker warning:

	net/bluetooth/l2cap_core.c:7613 l2cap_recv_acldata()
	error: double free of 'skb' (line 7557)

l2cap_recv_frame() consumes the skb.

Fixes: ad5747d4eed1 ("Bluetooth: l2cap: Process valid commands in too long frame")
Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
---
 net/bluetooth/l2cap_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 1bba7152fd70..5ca7ac43c58d 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -7556,7 +7556,7 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 			skb->len = len;
 			l2cap_recv_frame(conn, skb);
 			l2cap_conn_unreliable(conn, ECOMM);
-			goto drop;
+			goto unlock;
 		}
 
 		/* Append fragment into frame (with header) */
-- 
2.43.0

RE: Bluetooth: l2cap: Fix double free of 'skb'

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 1952 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=953999

---Test result---

Test Summary:
CheckPatch                    PENDING   0.39 seconds
GitLint                       PENDING   0.28 seconds
SubjectPrefix                 PASS      0.06 seconds
BuildKernel                   PASS      24.36 seconds
CheckAllWarning               PASS      31.05 seconds
CheckSparse                   PASS      29.79 seconds
BuildKernel32                 PASS      23.80 seconds
TestRunnerSetup               PASS      459.58 seconds
TestRunner_l2cap-tester       PASS      20.95 seconds
TestRunner_iso-tester         PASS      28.46 seconds
TestRunner_bnep-tester        PASS      4.73 seconds
TestRunner_mgmt-tester        FAIL      120.31 seconds
TestRunner_rfcomm-tester      PASS      19.23 seconds
TestRunner_sco-tester         PASS      33.25 seconds
TestRunner_ioctl-tester       PASS      9.35 seconds
TestRunner_mesh-tester        PASS      35.06 seconds
TestRunner_smp-tester         PASS      12.09 seconds
TestRunner_userchan-tester    PASS      4.94 seconds
IncrementalBuild              PENDING   0.78 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 490, Passed: 485 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
LL Privacy - Set Device Flag 1 (Device Privacy)      Failed       0.155 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: l2cap: Fix double free of 'skb'

[Luiz Augusto von Dentz]

Hi Frédéric,

On Wed, Apr 16, 2025 at 8:24 AM Frédéric Danis
<frederic.danis@collabora.com> wrote:
>
> Commit ad5747d4eed1 ("Bluetooth: l2cap: Process valid commands in too
> long frame") from Apr 14, 2025 (linux-next), leads to the following
> Smatch static checker warning:
>
>         net/bluetooth/l2cap_core.c:7613 l2cap_recv_acldata()
>         error: double free of 'skb' (line 7557)
>
> l2cap_recv_frame() consumes the skb.
>
> Fixes: ad5747d4eed1 ("Bluetooth: l2cap: Process valid commands in too long frame")
> Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
> ---
>  net/bluetooth/l2cap_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 1bba7152fd70..5ca7ac43c58d 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -7556,7 +7556,7 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
>                         skb->len = len;
>                         l2cap_recv_frame(conn, skb);
>                         l2cap_conn_unreliable(conn, ECOMM);
> -                       goto drop;
> +                       goto unlock;

I went ahead and fixed it up in place since I'm planning to send this
to net this week.

>                 }
>
>                 /* Append fragment into frame (with header) */
> --
> 2.43.0
>
>


-- 
Luiz Augusto von Dentz