[PATCH AUTOSEL 4.19 13/57] Bluetooth: Fix debugfs NULL pointer dereference

Sasha Levin
2019-03-30T01:29:19Z

From: Matias Karhumaa <matias.karhumaa@gmail.com>

[ Upstream commit 30d65e0804d58a03d1a8ea4e12c6fc07ed08218b ]

Fix crash caused by NULL pointer dereference when debugfs functions
le_max_key_read, le_max_key_size_write, le_min_key_size_read or
le_min_key_size_write and Bluetooth adapter was powered off.

Fix is to move max_key_size and min_key_size from smp_dev to hci_dev.
At the same time they were renamed to le_max_key_size and
le_min_key_size.

BUG: unable to handle kernel NULL pointer dereference at 00000000000002e8
PGD 0 P4D 0
Oops: 0000 [#24] SMP PTI
CPU: 2 PID: 6255 Comm: cat Tainted: G D OE 4.18.9-200.fc28.x86_64 #1
Hardware name: LENOVO 4286CTO/4286CTO, BIOS 8DET76WW (1.46 ) 06/21/2018
RIP: 0010:le_max_key_size_read+0x45/0xb0 [bluetooth]
Code: 00 00 00 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 31 c0 48 8b 87 c8 00 00 00 48 8d 7c 24 04 48 8b 80 48 0a 00 00 <48> 8b 80 e8 02 00 00 0f b6 48 52 e8 fb b6 b3 ed be 04 00 00 00 48
RSP: 0018:ffffab23c3ff3df0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00007f0b4ca2e000 RCX: ffffab23c3ff3f08
RDX: ffffffffc0ddb033 RSI: 0000000000000004 RDI: ffffab23c3ff3df4
RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffab23c3ff3ed8 R11: 0000000000000000 R12: ffffab23c3ff3f08
R13: 00007f0b4ca2e000 R14: 0000000000020000 R15: ffffab23c3ff3f08
FS: 00007f0b4ca0f540(0000) GS:ffff91bd5e280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000002e8 CR3: 00000000629fa006 CR4: 00000000000606e0
Call Trace:
full_proxy_read+0x53/0x80
__vfs_read+0x36/0x180
vfs_read+0x8a/0x140
ksys_read+0x4f/0xb0
do_syscall_64+0x5b/0x160
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Matias Karhumaa <matias.karhumaa@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/bluetooth/hci_core.h | 2 ++
net/bluetooth/hci_core.c | 2 ++
net/bluetooth/smp.c | 23 +++++++++--------------
3 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 0db1b9b428b7..1dfb75057580 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -259,6 +259,8 @@ struct hci_dev {
__u16 le_max_tx_time;
__u16 le_max_rx_len;
__u16 le_max_rx_time;
+ __u8 le_max_key_size;
+ __u8 le_min_key_size;
__u16 discov_interleaved_timeout;
__u16 conn_info_min_age;
__u16 conn_info_max_age;
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 74b29c7d841c..a06f03047717 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3084,6 +3084,8 @@ struct hci_dev *hci_alloc_dev(void)
hdev->le_max_tx_time = 0x0148;
hdev->le_max_rx_len = 0x001b;
hdev->le_max_rx_time = 0x0148;
+ hdev->le_max_key_size = SMP_MAX_ENC_KEY_SIZE;
+ hdev->le_min_key_size = SMP_MIN_ENC_KEY_SIZE;
hdev->le_tx_def_phys = HCI_LE_SET_PHY_1M;
hdev->le_rx_def_phys = HCI_LE_SET_PHY_1M;

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 73f7211d0431..a1c1b7e8a45c 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -88,9 +88,6 @@ struct smp_dev {
u8 local_rand[16];
bool debug_key;

- u8 min_key_size;
- u8 max_key_size;
-
struct crypto_cipher *tfm_aes;
struct crypto_shash *tfm_cmac;
struct crypto_kpp *tfm_ecdh;
@@ -720,7 +717,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
if (rsp == NULL) {
req->io_capability = conn->hcon->io_capability;
req->oob_flag = oob_flag;
- req->max_key_size = SMP_DEV(hdev)->max_key_size;
+ req->max_key_size = hdev->le_max_key_size;
req->init_key_dist = local_dist;
req->resp_key_dist = remote_dist;
req->auth_req = (authreq & AUTH_REQ_MASK(hdev));
@@ -731,7 +728,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,

rsp->io_capability = conn->hcon->io_capability;
rsp->oob_flag = oob_flag;
- rsp->max_key_size = SMP_DEV(hdev)->max_key_size;
+ rsp->max_key_size = hdev->le_max_key_size;
rsp->init_key_dist = req->init_key_dist & remote_dist;
rsp->resp_key_dist = req->resp_key_dist & local_dist;
rsp->auth_req = (authreq & AUTH_REQ_MASK(hdev));
@@ -745,7 +742,7 @@ static u8 check_enc_key_size(struct l2cap_conn *conn, __u8 max_key_size)
struct hci_dev *hdev = conn->hcon->hdev;
struct smp_chan *smp = chan->data;

- if (max_key_size > SMP_DEV(hdev)->max_key_size ||
+ if (max_key_size > hdev->le_max_key_size ||
max_key_size < SMP_MIN_ENC_KEY_SIZE)
return SMP_ENC_KEY_SIZE;

@@ -3264,8 +3261,6 @@ static struct l2cap_chan *smp_add_cid(struct hci_dev *hdev, u16 cid)
smp->tfm_aes = tfm_aes;
smp->tfm_cmac = tfm_cmac;
smp->tfm_ecdh = tfm_ecdh;
- smp->min_key_size = SMP_MIN_ENC_KEY_SIZE;
- smp->max_key_size = SMP_MAX_ENC_KEY_SIZE;

create_chan:
chan = l2cap_chan_create();
@@ -3391,7 +3386,7 @@ static ssize_t le_min_key_size_read(struct file *file,
struct hci_dev *hdev = file->private_data;
char buf[4];

- snprintf(buf, sizeof(buf), "%2u\n", SMP_DEV(hdev)->min_key_size);
+ snprintf(buf, sizeof(buf), "%2u\n", hdev->le_min_key_size);

return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
}
@@ -3412,11 +3407,11 @@ static ssize_t le_min_key_size_write(struct file *file,

sscanf(buf, "%hhu", &key_size);

- if (key_size > SMP_DEV(hdev)->max_key_size ||
+ if (key_size > hdev->le_max_key_size ||
key_size < SMP_MIN_ENC_KEY_SIZE)
return -EINVAL;

- SMP_DEV(hdev)->min_key_size = key_size;
+ hdev->le_min_key_size = key_size;

return count;
}
@@ -3435,7 +3430,7 @@ static ssize_t le_max_key_size_read(struct file *file,
struct hci_dev *hdev = file->private_data;
char buf[4];

- snprintf(buf, sizeof(buf), "%2u\n", SMP_DEV(hdev)->max_key_size);
+ snprintf(buf, sizeof(buf), "%2u\n", hdev->le_max_key_size);

return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
}
@@ -3457,10 +3452,10 @@ static ssize_t le_max_key_size_write(struct file *file,
sscanf(buf, "%hhu", &key_size);

if (key_size > SMP_MAX_ENC_KEY_SIZE ||
- key_size < SMP_DEV(hdev)->min_key_size)
+ key_size < hdev->le_min_key_size)
return -EINVAL;

- SMP_DEV(hdev)->max_key_size = key_size;
+ hdev->le_max_key_size = key_size;

return count;
}
--
2.19.1