Hi Luiz, could you review this patch?
This patch prevents a div-by-zero error and potential int overflow by
adding a range check for MTU in hci_cc_le_read_buffer_size() and
hci_cc_le_read_buffer_size_v2().
Also, hci_connect_le() will refuse to allocate hcon if the MTU is not in
the valid range.
Bug description:
l2cap_le_flowctl_init() can cause both div-by-zero and an integer overflow.
l2cap_le_flowctl_init()
chan->mps = min_t(u16, chan->imtu, chan->conn->mtu - L2CAP_HDR_SIZE);
chan->rx_credits = (chan->imtu / chan->mps) + 1; <- div-by-zero
Here, chan->conn->mtu could be less than or equal to L2CAP_HDR_SIZE (4).
If mtu is 4, it causes div-by-zero. If mtu is less than 4, it causes an
integer overflow.
How mtu could have such low value:
hci_cc_le_read_buffer_size()
hdev->le_mtu = __le16_to_cpu(rp->le_mtu);
l2cap_conn_add()
conn->mtu = hcon->hdev->le_mtu;
As shown, mtu is an input from an HCI device. So, any HCI device can
set mtu value to any value, such as lower than 4.
According to the spec v5.4 7.8.2 LE Read Buffer Size command, the value
should be fall in [0x001b, 0xffff].
Thank you,
Sungwoo.
divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 PID: 67 Comm: kworker/u5:0 Tainted: G W 6.9.0-rc5+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: hci0 hci_rx_work
RIP: 0010:l2cap_le_flowctl_init+0x19e/0x3f0 net/bluetooth/l2cap_core.c:547
Code: e8 17 17 0c 00 66 41 89 9f 84 00 00 00 bf 01 00 00 00 41 b8 02 00 00 00 4c 89 fe 4c 89 e2 89 d9 e8 27 17 0c 00 44 89 f0 31 d2 <66> f7 f3 89 c3 ff c3 4d 8d b7 88 00 00 00 4c 89 f0 48 c1 e8 03 42
RSP: 0018:ffff88810bc0f858 EFLAGS: 00010246
RAX: 00000000000002a0 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffff88810bc0f7c0 RDI: ffffc90002dcb66f
RBP: ffff88810bc0f880 R08: aa69db2dda70ff01 R09: 0000ffaaaaaaaaaa
R10: 0084000000ffaaaa R11: 0000000000000000 R12: ffff88810d65a084
R13: dffffc0000000000 R14: 00000000000002a0 R15: ffff88810d65a000
FS: 0000000000000000(0000) GS:ffff88811ac00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000100 CR3: 0000000103268003 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
l2cap_le_connect_req net/bluetooth/l2cap_core.c:4902 [inline]
l2cap_le_sig_cmd net/bluetooth/l2cap_core.c:5420 [inline]
l2cap_le_sig_channel net/bluetooth/l2cap_core.c:5486 [inline]
l2cap_recv_frame+0xe59d/0x11710 net/bluetooth/l2cap_core.c:6809
l2cap_recv_acldata+0x544/0x10a0 net/bluetooth/l2cap_core.c:7506
hci_acldata_packet net/bluetooth/hci_core.c:3939 [inline]
hci_rx_work+0x5e5/0xb20 net/bluetooth/hci_core.c:4176
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0x90f/0x1530 kernel/workqueue.c:3335
worker_thread+0x926/0xe70 kernel/workqueue.c:3416
kthread+0x2e3/0x380 kernel/kthread.c:388
ret_from_fork+0x5c/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
Signed-off-by: Sungwoo Kim <[email protected]>
---
v1 -> v2:
- Reply with an error code if a given MTU is not valid.
- Refuse hcon allocation if MTU is not still valid.
include/net/bluetooth/hci.h | 6 ++++++
net/bluetooth/hci_conn.c | 4 ++++
net/bluetooth/hci_event.c | 6 ++++++
3 files changed, 16 insertions(+)
diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 5c12761cb..a7bc07e9c 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -1666,6 +1666,12 @@ struct hci_cp_le_set_event_mask {
__u8 mask[8];
} __packed;
+/* BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 4, Part E
+ * 7.8.2 LE Read Buffer Size command
+ */
+#define HCI_MIN_LE_MTU 0x001b
+#define HCI_MAX_LE_MTU 0xFFFF
+
#define HCI_OP_LE_READ_BUFFER_SIZE 0x2002
struct hci_rp_le_read_buffer_size {
__u8 status;
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 05346250f..0b86a7452 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1277,6 +1277,10 @@ struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
return ERR_PTR(-EOPNOTSUPP);
}
+ /* Check the mtu is valid */
+ if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
+ return ERR_PTR(-ECONNREFUSED);
+
/* Since the controller supports only one LE connection attempt at a
* time, we return -EBUSY if there is any connection attempt running.
*/
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 4a27e4a17..a8563cbe2 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -1263,6 +1263,9 @@ static u8 hci_cc_le_read_buffer_size(struct hci_dev *hdev, void *data,
BT_DBG("%s le mtu %d:%d", hdev->name, hdev->le_mtu, hdev->le_pkts);
+ if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
+ return HCI_ERROR_INVALID_PARAMETERS;
+
return rp->status;
}
@@ -3821,6 +3824,9 @@ static u8 hci_cc_le_read_buffer_size_v2(struct hci_dev *hdev, void *data,
BT_DBG("%s acl mtu %d:%d iso mtu %d:%d", hdev->name, hdev->acl_mtu,
hdev->acl_pkts, hdev->iso_mtu, hdev->iso_pkts);
+ if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
+ return HCI_ERROR_INVALID_PARAMETERS;
+
return rp->status;
}
--
2.34.1
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=849562
---Test result---
Test Summary:
CheckPatch FAIL 1.30 seconds
GitLint FAIL 0.52 seconds
SubjectPrefix PASS 0.13 seconds
BuildKernel PASS 29.98 seconds
CheckAllWarning PASS 34.78 seconds
CheckSparse WARNING 41.73 seconds
CheckSmatch FAIL 36.49 seconds
BuildKernel32 PASS 29.28 seconds
TestRunnerSetup PASS 525.06 seconds
TestRunner_l2cap-tester PASS 23.57 seconds
TestRunner_iso-tester PASS 31.38 seconds
TestRunner_bnep-tester PASS 4.79 seconds
TestRunner_mgmt-tester FAIL 119.48 seconds
TestRunner_rfcomm-tester PASS 7.26 seconds
TestRunner_sco-tester PASS 15.00 seconds
TestRunner_ioctl-tester PASS 7.70 seconds
TestRunner_mesh-tester FAIL 5.98 seconds
TestRunner_smp-tester PASS 6.85 seconds
TestRunner_userchan-tester PASS 4.94 seconds
IncrementalBuild PASS 28.88 seconds
Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
[v2] Bluetooth: L2CAP: Fix div-by-zero in l2cap_le_flowctl_init()
WARNING: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#122:
CPU: 0 PID: 67 Comm: kworker/u5:0 Tainted: G W 6.9.0-rc5+ #20
total: 0 errors, 1 warnings, 0 checks, 40 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
/github/workspace/src/src/13650236.patch has style problems, please review.
NOTE: Ignored message types: UNKNOWN_COMMIT_ID
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v2] Bluetooth: L2CAP: Fix div-by-zero in l2cap_le_flowctl_init()
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
44: B1 Line exceeds max length (199>80): "Code: e8 17 17 0c 00 66 41 89 9f 84 00 00 00 bf 01 00 00 00 41 b8 02 00 00 00 4c 89 fe 4c 89 e2 89 d9 e8 27 17 0c 00 44 89 f0 31 d2 <66> f7 f3 89 c3 ff c3 4d 8d b7 88 00 00 00 4c 89 f0 48 c1 e8 03 42"
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/hci_event.c: note: in included file (through include/net/bluetooth/hci_core.h):
##############################
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....
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: drivers/bluetooth/bpa10x.o] Error 139
make[4]: *** Deleting file 'drivers/bluetooth/bpa10x.o'
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_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 - Start Discovery 2 (Disable RL) Failed 0.163 seconds
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 9 (90.0%), Failed: 1, Not Run: 0
Failed Test Cases
Mesh - Send cancel - 2 Failed 0.099 seconds
---
Regards,
Linux Bluetooth
Hi Sungwoo,
On Wed, May 1, 2024 at 12:32 AM Sungwoo Kim <[email protected]> wrote:
>
> Hi Luiz, could you review this patch?
>
> This patch prevents a div-by-zero error and potential int overflow by
> adding a range check for MTU in hci_cc_le_read_buffer_size() and
> hci_cc_le_read_buffer_size_v2().
> Also, hci_connect_le() will refuse to allocate hcon if the MTU is not in
> the valid range.
>
> Bug description:
>
> l2cap_le_flowctl_init() can cause both div-by-zero and an integer overflow.
>
> l2cap_le_flowctl_init()
> chan->mps = min_t(u16, chan->imtu, chan->conn->mtu - L2CAP_HDR_SIZE);
> chan->rx_credits = (chan->imtu / chan->mps) + 1; <- div-by-zero
>
> Here, chan->conn->mtu could be less than or equal to L2CAP_HDR_SIZE (4).
> If mtu is 4, it causes div-by-zero. If mtu is less than 4, it causes an
> integer overflow.
>
> How mtu could have such low value:
>
> hci_cc_le_read_buffer_size()
> hdev->le_mtu = __le16_to_cpu(rp->le_mtu);
>
> l2cap_conn_add()
> conn->mtu = hcon->hdev->le_mtu;
>
> As shown, mtu is an input from an HCI device. So, any HCI device can
> set mtu value to any value, such as lower than 4.
> According to the spec v5.4 7.8.2 LE Read Buffer Size command, the value
> should be fall in [0x001b, 0xffff].
>
> Thank you,
> Sungwoo.
>
> divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 0 PID: 67 Comm: kworker/u5:0 Tainted: G W 6.9.0-rc5+ #20
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> Workqueue: hci0 hci_rx_work
> RIP: 0010:l2cap_le_flowctl_init+0x19e/0x3f0 net/bluetooth/l2cap_core.c:547
> Code: e8 17 17 0c 00 66 41 89 9f 84 00 00 00 bf 01 00 00 00 41 b8 02 00 00 00 4c 89 fe 4c 89 e2 89 d9 e8 27 17 0c 00 44 89 f0 31 d2 <66> f7 f3 89 c3 ff c3 4d 8d b7 88 00 00 00 4c 89 f0 48 c1 e8 03 42
> RSP: 0018:ffff88810bc0f858 EFLAGS: 00010246
> RAX: 00000000000002a0 RBX: 0000000000000000 RCX: dffffc0000000000
> RDX: 0000000000000000 RSI: ffff88810bc0f7c0 RDI: ffffc90002dcb66f
> RBP: ffff88810bc0f880 R08: aa69db2dda70ff01 R09: 0000ffaaaaaaaaaa
> R10: 0084000000ffaaaa R11: 0000000000000000 R12: ffff88810d65a084
> R13: dffffc0000000000 R14: 00000000000002a0 R15: ffff88810d65a000
> FS: 0000000000000000(0000) GS:ffff88811ac00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020000100 CR3: 0000000103268003 CR4: 0000000000770ef0
> PKRU: 55555554
> Call Trace:
> <TASK>
> l2cap_le_connect_req net/bluetooth/l2cap_core.c:4902 [inline]
> l2cap_le_sig_cmd net/bluetooth/l2cap_core.c:5420 [inline]
> l2cap_le_sig_channel net/bluetooth/l2cap_core.c:5486 [inline]
> l2cap_recv_frame+0xe59d/0x11710 net/bluetooth/l2cap_core.c:6809
> l2cap_recv_acldata+0x544/0x10a0 net/bluetooth/l2cap_core.c:7506
> hci_acldata_packet net/bluetooth/hci_core.c:3939 [inline]
> hci_rx_work+0x5e5/0xb20 net/bluetooth/hci_core.c:4176
> process_one_work kernel/workqueue.c:3254 [inline]
> process_scheduled_works+0x90f/0x1530 kernel/workqueue.c:3335
> worker_thread+0x926/0xe70 kernel/workqueue.c:3416
> kthread+0x2e3/0x380 kernel/kthread.c:388
> ret_from_fork+0x5c/0x90 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
>
> Signed-off-by: Sungwoo Kim <[email protected]>
> ---
> v1 -> v2:
> - Reply with an error code if a given MTU is not valid.
> - Refuse hcon allocation if MTU is not still valid.
>
> include/net/bluetooth/hci.h | 6 ++++++
> net/bluetooth/hci_conn.c | 4 ++++
> net/bluetooth/hci_event.c | 6 ++++++
> 3 files changed, 16 insertions(+)
>
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index 5c12761cb..a7bc07e9c 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -1666,6 +1666,12 @@ struct hci_cp_le_set_event_mask {
> __u8 mask[8];
> } __packed;
>
> +/* BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 4, Part E
> + * 7.8.2 LE Read Buffer Size command
> + */
> +#define HCI_MIN_LE_MTU 0x001b
> +#define HCI_MAX_LE_MTU 0xFFFF
Don't think we really need the MAX value here since it is that same as
the maximum field can assume so doing x > MAX is sort of useless as it
loops around if that happens.
> #define HCI_OP_LE_READ_BUFFER_SIZE 0x2002
> struct hci_rp_le_read_buffer_size {
> __u8 status;
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index 05346250f..0b86a7452 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -1277,6 +1277,10 @@ struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
> return ERR_PTR(-EOPNOTSUPP);
> }
>
> + /* Check the mtu is valid */
> + if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
> + return ERR_PTR(-ECONNREFUSED);
> +
That probably needs to be done on hci_conn_add if we want to capture
both incoming and outgoing.
> /* Since the controller supports only one LE connection attempt at a
> * time, we return -EBUSY if there is any connection attempt running.
> */
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 4a27e4a17..a8563cbe2 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -1263,6 +1263,9 @@ static u8 hci_cc_le_read_buffer_size(struct hci_dev *hdev, void *data,
>
> BT_DBG("%s le mtu %d:%d", hdev->name, hdev->le_mtu, hdev->le_pkts);
>
> + if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
> + return HCI_ERROR_INVALID_PARAMETERS;
Value 0x00 means 'No dedicated LE Buffer exists. Use the
HCI_Read_Buffer_Size command.' so it is not invalid to return it.
> return rp->status;
> }
>
> @@ -3821,6 +3824,9 @@ static u8 hci_cc_le_read_buffer_size_v2(struct hci_dev *hdev, void *data,
> BT_DBG("%s acl mtu %d:%d iso mtu %d:%d", hdev->name, hdev->acl_mtu,
> hdev->acl_pkts, hdev->iso_mtu, hdev->iso_pkts);
>
> + if (hdev->le_mtu < HCI_MIN_LE_MTU || HCI_MAX_LE_MTU < hdev->le_mtu)
> + return HCI_ERROR_INVALID_PARAMETERS;
Ditto, this should really be:
if (hdev->le_mtu && hdev->le_mtu < HCI_MIN_LE_MTU)
> return rp->status;
> }
>
> --
> 2.34.1
>
--
Luiz Augusto von Dentz