Bluetooth: l2cap: Add missing chan lock in l2cap_ecred_reconf_rsp

l2cap_ecred_reconf_rsp() calls l2cap_chan_del() without holding l2cap_chan_lock(). Every other l2cap_chan_del() caller in the file acquires the lock first. A remote BLE device can send a crafted L2CAP ECRED reconfiguration response to corrupt the channel list while another thread is iterating it.

Add l2cap_chan_hold() and l2cap_chan_lock() before l2cap_chan_del(), and l2cap_chan_unlock() and l2cap_chan_put() after, matching the pattern used in l2cap_ecred_conn_rsp() and l2cap_conn_del().

---
 net/bluetooth/l2cap_core.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 95c65fece39b..82989c1319c4 100644
@@ -5473,7 +5473,13 @@ static inline int l2cap_ecred_reconf_rsp(struct l2cap_conn *conn,
 		if (chan->ident != cmd->ident)
 			continue;
 
+		l2cap_chan_hold(chan);
+		l2cap_chan_lock(chan);
+
 		l2cap_chan_del(chan, ECONNRESET);
+
+		l2cap_chan_unlock(chan);
+		l2cap_chan_put(chan);
 	}
 
 	return 0;

2.53.0

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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=1077454

---Test result---

Test Summary:

CheckPatch                    PENDING   0.40 seconds
GitLint                       PENDING   0.26 seconds
SubjectPrefix                 PASS      0.10 seconds
BuildKernel                   PASS      26.57 seconds
CheckAllWarning               PASS      29.30 seconds
CheckSparse                   PASS      27.78 seconds
BuildKernel32                 PASS      25.55 seconds
TestRunnerSetup               PASS      564.88 seconds
TestRunner_l2cap-tester       PASS      27.50 seconds
TestRunner_iso-tester         PASS      37.34 seconds
TestRunner_bnep-tester        PASS      6.40 seconds
TestRunner_mgmt-tester        FAIL      112.72 seconds
TestRunner_rfcomm-tester      PASS      9.51 seconds
TestRunner_sco-tester         FAIL      14.32 seconds
TestRunner_ioctl-tester       PASS      10.22 seconds
TestRunner_mesh-tester        FAIL      13.09 seconds
TestRunner_smp-tester         PASS      8.60 seconds
TestRunner_userchan-tester    PASS      6.70 seconds
IncrementalBuild              PENDING   0.48 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: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
Read Exp Feature - Success Failed 0.103 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    1.996 seconds
Mesh - Send cancel - 2                               Timed out    2.000 seconds

##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series Output:

---
Regards,
Linux Bluetooth