[PATCH] Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()

[PATCH] Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()

[Hyunwoo Kim]

l2cap_ecred_data_rcv() reads the SDU length field from skb->data using
get_unaligned_le16() without first verifying that skb contains at least
L2CAP_SDULEN_SIZE (2) bytes. When skb->len is less than 2, this reads
past the valid data in the skb.

The ERTM reassembly path correctly calls pskb_may_pull() before reading
the SDU length (l2cap_reassemble_sdu, L2CAP_SAR_START case). Apply the
same validation to the Enhanced Credit Based Flow Control data path.

Fixes: aac23bf63659 ("Bluetooth: Implement LE L2CAP reassembly")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
---
 net/bluetooth/l2cap_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index ad98db9632fd..99e9aa104507 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -6682,6 +6682,11 @@ static int l2cap_ecred_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
 	if (!chan->sdu) {
 		u16 sdu_len;
 
+		if (!pskb_may_pull(skb, L2CAP_SDULEN_SIZE)) {
+			err = -EINVAL;
+			goto failed;
+		}
+
 		sdu_len = get_unaligned_le16(skb->data);
 		skb_pull(skb, L2CAP_SDULEN_SIZE);
 
-- 
2.43.0

RE: Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()

[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=1065909

---Test result---

Test Summary:
CheckPatch                    PENDING   0.39 seconds
GitLint                       PENDING   0.54 seconds
SubjectPrefix                 PASS      0.07 seconds
BuildKernel                   PASS      26.50 seconds
CheckAllWarning               PASS      28.83 seconds
CheckSparse                   WARNING   32.60 seconds
BuildKernel32                 PASS      25.72 seconds
TestRunnerSetup               PASS      562.46 seconds
TestRunner_l2cap-tester       PASS      28.63 seconds
TestRunner_iso-tester         PASS      94.11 seconds
TestRunner_bnep-tester        PASS      6.36 seconds
TestRunner_mgmt-tester        FAIL      113.01 seconds
TestRunner_rfcomm-tester      PASS      9.50 seconds
TestRunner_sco-tester         FAIL      14.56 seconds
TestRunner_ioctl-tester       PASS      10.29 seconds
TestRunner_mesh-tester        FAIL      12.46 seconds
TestRunner_smp-tester         PASS      8.71 seconds
TestRunner_userchan-tester    PASS      6.75 seconds
IncrementalBuild              PENDING   1.07 seconds

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

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

##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/l2cap_core.c:7803:1: error: bad constant expressionnet/bluetooth/l2cap_core.c:7804:1: error: bad constant expressionnet/bluetooth/l2cap_core.c:7806:1: error: bad constant expressionnet/bluetooth/l2cap_core.c:7807:1: error: bad constant expression
##############################
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       0.101 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context at net/core/sock.c:3782
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
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    2.751 seconds
Mesh - Send cancel - 2                               Timed out    1.992 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()

[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 Fri, 13 Mar 2026 05:22:39 +0900 you wrote:
> l2cap_ecred_data_rcv() reads the SDU length field from skb->data using
> get_unaligned_le16() without first verifying that skb contains at least
> L2CAP_SDULEN_SIZE (2) bytes. When skb->len is less than 2, this reads
> past the valid data in the skb.
> 
> The ERTM reassembly path correctly calls pskb_may_pull() before reading
> the SDU length (l2cap_reassemble_sdu, L2CAP_SAR_START case). Apply the
> same validation to the Enhanced Credit Based Flow Control data path.
> 
> [...]

Here is the summary with links:
  - Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()
    https://git.kernel.org/bluetooth/bluetooth-next/c/a480f2bbc7c2

You are awesome, thank you!
-- 
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