[next] Bluetooth: hci_conn: Use __counted_by() and avoid -Wfamnae warning

Commit Message

Gustavo A. R. Silva May 2, 2024, 4:22 p.m. UTC

Prepare for the coming implementation by GCC and Clang of the
__counted_by attribute. Flexible array members annotated with
__counted_by can have their accesses bounds-checked at run-time
via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
(for strcpy/memcpy-family functions).

Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are
getting ready to enable it globally.

So, use the `DEFINE_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.

With these changes, fix the following warning:
net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Link: https://github.com/KSPP/linux/issues/202
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
---
 include/net/bluetooth/hci.h |  2 +-
 net/bluetooth/hci_conn.c    | 38 ++++++++++++++++---------------------
 2 files changed, 17 insertions(+), 23 deletions(-)

Comments

[e-mail] May 2, 2024, 4:59 p.m. UTC | #1

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=849960

---Test result---

Test Summary:
CheckPatch                    PASS      1.64 seconds
GitLint                       FAIL      0.68 seconds
SubjectPrefix                 PASS      0.07 seconds
BuildKernel                   PASS      30.02 seconds
CheckAllWarning               PASS      32.49 seconds
CheckSparse                   PASS      38.56 seconds
CheckSmatch                   FAIL      35.75 seconds
BuildKernel32                 PASS      28.86 seconds
TestRunnerSetup               PASS      529.44 seconds
TestRunner_l2cap-tester       PASS      20.60 seconds
TestRunner_iso-tester         FAIL      32.45 seconds
TestRunner_bnep-tester        PASS      4.69 seconds
TestRunner_mgmt-tester        FAIL      112.58 seconds
TestRunner_rfcomm-tester      PASS      7.45 seconds
TestRunner_sco-tester         PASS      15.15 seconds
TestRunner_ioctl-tester       PASS      7.86 seconds
TestRunner_mesh-tester        PASS      5.89 seconds
TestRunner_smp-tester         PASS      6.77 seconds
TestRunner_userchan-tester    PASS      5.07 seconds
IncrementalBuild              PASS      28.43 seconds

Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[next] Bluetooth: hci_conn: Use __counted_by() and avoid -Wfamnae warning

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
18: B1 Line exceeds max length (158>80): "net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]"
##############################
Test: CheckSmatch - FAIL
Desc: Run smatch tool with source
Output:

Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: net/bluetooth/hci_core.o] Error 139
make[4]: *** Deleting file 'net/bluetooth/hci_core.o'
make[3]: *** [scripts/Makefile.build:485: net/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: net] Error 2
make[2]: *** Waiting for unfinished jobs....
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: drivers/bluetooth/bcm203x.o] Error 139
make[4]: *** Deleting file 'drivers/bluetooth/bcm203x.o'
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [scripts/Makefile.build:485: drivers/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: drivers] Error 2
make[1]: *** [/github/workspace/src/src/Makefile:1919: .] Error 2
make: *** [Makefile:240: __sub-make] Error 2
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
Total: 122, Passed: 121 (99.2%), Failed: 1, Not Run: 0

Failed Test Cases
ISO Connect Suspend - Success                        Failed       4.189 seconds
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 489 (99.4%), Failed: 1, Not Run: 2

Failed Test Cases
LL Privacy - Add Device 6 (RL is full)               Failed       0.191 seconds


---
Regards,
Linux Bluetooth

Kees Cook May 2, 2024, 5:45 p.m. UTC | #2

On Thu, May 02, 2024 at 10:22:00AM -0600, Gustavo A. R. Silva wrote:
> Prepare for the coming implementation by GCC and Clang of the
> __counted_by attribute. Flexible array members annotated with
> __counted_by can have their accesses bounds-checked at run-time
> via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
> (for strcpy/memcpy-family functions).
> 
> Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are
> getting ready to enable it globally.
> 
> So, use the `DEFINE_FLEX()` helper for an on-stack definition of
> a flexible structure where the size of the flexible-array member
> is known at compile-time, and refactor the rest of the code,
> accordingly.
> 
> With these changes, fix the following warning:
> net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> 
> Link: https://github.com/KSPP/linux/issues/202
> Signed-off-by: Gustavo A. R. Silva <[e-mail]>

Nice! This looks really clean; I'll point people at this patch when they
want to see these kinds of conversions. It has it all! :)

Reviewed-by: Kees Cook <[e-mail]>

Gustavo A. R. Silva May 3, 2024, 2:53 a.m. UTC | #3

>> So, use the `DEFINE_FLEX()` helper for an on-stack definition of
>> a flexible structure where the size of the flexible-array member
>> is known at compile-time, and refactor the rest of the code,
>> accordingly.
>>
>> With these changes, fix the following warning:
>> net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>
>> Link: https://github.com/KSPP/linux/issues/202
>> Signed-off-by: Gustavo A. R. Silva <[e-mail]>
> 
> Nice! This looks really clean; I'll point people at this patch when they
> want to see these kinds of conversions. It has it all! :)

I really enjoyed writing it!

It was great to find out I could remove that global struct. :)

> 
> Reviewed-by: Kees Cook <[e-mail]>
> 

Thanks!
--
Gustavo

[e-mail] May 3, 2024, 5 p.m. UTC | #4

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[e-mail]>:

On Thu, 2 May 2024 10:22:00 -0600 you wrote:
> Prepare for the coming implementation by GCC and Clang of the
> __counted_by attribute. Flexible array members annotated with
> __counted_by can have their accesses bounds-checked at run-time
> via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
> (for strcpy/memcpy-family functions).
> 
> Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are
> getting ready to enable it globally.
> 
> [...]

Here is the summary with links:
  - [next] Bluetooth: hci_conn: Use __counted_by() and avoid -Wfamnae warning
    https://git.kernel.org/bluetooth/bluetooth-next/c/6d18d5b03ee1

You are awesome, thank you!

Patch

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index c4c6b8810701..e6838321f4d9 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -2144,7 +2144,7 @@  struct hci_cp_le_set_cig_params {
 	__le16  c_latency;
 	__le16  p_latency;
 	__u8    num_cis;
-	struct hci_cis_params cis[];
+	struct hci_cis_params cis[] __counted_by(num_cis);
 } __packed;
 
 struct hci_rp_le_set_cig_params {
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index c508609be105..6e60e8287956 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -665,11 +665,6 @@  static void le_conn_timeout(struct work_struct *work)
 	hci_abort_conn(conn, HCI_ERROR_REMOTE_USER_TERM);
 }
 
-struct iso_cig_params {
-	struct hci_cp_le_set_cig_params cp;
-	struct hci_cis_params cis[0x1f];
-};
-
 struct iso_list_data {
 	union {
 		u8  cig;
@@ -1725,34 +1720,33 @@  static int hci_le_create_big(struct hci_conn *conn, struct bt_iso_qos *qos)
 
 static int set_cig_params_sync(struct hci_dev *hdev, void *data)
 {
+	DEFINE_FLEX(struct hci_cp_le_set_cig_params, pdu, cis, num_cis, 0x1f);
 	u8 cig_id = PTR_UINT(data);
 	struct hci_conn *conn;
 	struct bt_iso_qos *qos;
-	struct iso_cig_params pdu;
+	u8 aux_num_cis = 0;
 	u8 cis_id;
 
 	conn = hci_conn_hash_lookup_cig(hdev, cig_id);
 	if (!conn)
 		return 0;
 
-	memset(&pdu, 0, sizeof(pdu));
-
 	qos = &conn->iso_qos;
-	pdu.cp.cig_id = cig_id;
-	hci_cpu_to_le24(qos->ucast.out.interval, pdu.cp.c_interval);
-	hci_cpu_to_le24(qos->ucast.in.interval, pdu.cp.p_interval);
-	pdu.cp.sca = qos->ucast.sca;
-	pdu.cp.packing = qos->ucast.packing;
-	pdu.cp.framing = qos->ucast.framing;
-	pdu.cp.c_latency = cpu_to_le16(qos->ucast.out.latency);
-	pdu.cp.p_latency = cpu_to_le16(qos->ucast.in.latency);
+	pdu->cig_id = cig_id;
+	hci_cpu_to_le24(qos->ucast.out.interval, pdu->c_interval);
+	hci_cpu_to_le24(qos->ucast.in.interval, pdu->p_interval);
+	pdu->sca = qos->ucast.sca;
+	pdu->packing = qos->ucast.packing;
+	pdu->framing = qos->ucast.framing;
+	pdu->c_latency = cpu_to_le16(qos->ucast.out.latency);
+	pdu->p_latency = cpu_to_le16(qos->ucast.in.latency);
 
 	/* Reprogram all CIS(s) with the same CIG, valid range are:
 	 * num_cis: 0x00 to 0x1F
 	 * cis_id: 0x00 to 0xEF
 	 */
 	for (cis_id = 0x00; cis_id < 0xf0 &&
-	     pdu.cp.num_cis < ARRAY_SIZE(pdu.cis); cis_id++) {
+	     aux_num_cis < pdu->num_cis; cis_id++) {
 		struct hci_cis_params *cis;
 
 		conn = hci_conn_hash_lookup_cis(hdev, NULL, 0, cig_id, cis_id);
@@ -1761,7 +1755,7 @@  static int set_cig_params_sync(struct hci_dev *hdev, void *data)
 
 		qos = &conn->iso_qos;
 
-		cis = &pdu.cis[pdu.cp.num_cis++];
+		cis = &pdu->cis[aux_num_cis++];
 		cis->cis_id = cis_id;
 		cis->c_sdu  = cpu_to_le16(conn->iso_qos.ucast.out.sdu);
 		cis->p_sdu  = cpu_to_le16(conn->iso_qos.ucast.in.sdu);
@@ -1772,14 +1766,14 @@  static int set_cig_params_sync(struct hci_dev *hdev, void *data)
 		cis->c_rtn  = qos->ucast.out.rtn;
 		cis->p_rtn  = qos->ucast.in.rtn;
 	}
+	pdu->num_cis = aux_num_cis;
 
-	if (!pdu.cp.num_cis)
+	if (!pdu->num_cis)
 		return 0;
 
 	return __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_CIG_PARAMS,
-				     sizeof(pdu.cp) +
-				     pdu.cp.num_cis * sizeof(pdu.cis[0]), &pdu,
-				     HCI_CMD_TIMEOUT);
+				     struct_size(pdu, cis, pdu->num_cis),
+				     pdu, HCI_CMD_TIMEOUT);
 }
 
 static bool hci_le_set_cig_params(struct hci_conn *conn, struct bt_iso_qos *qos)