[PATCH 4.19 159/421] Bluetooth: mgmt: Fix slab-out-of-bounds in tlv_data_is_valid

Greg Kroah-Hartman
2021-07-19T16:17:45Z

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

[ Upstream commit 799acb9347915bfe4eac0ff2345b468f0a1ca207 ]

This fixes parsing of LTV entries when the length is 0.

Found with:

tools/mgmt-tester -s "Add Advertising - Success (ScRsp only)"

Add Advertising - Success (ScRsp only) - run
Sending Add Advertising (0x003e)
Test condition added, total 1
[ 11.004577] ==================================================================
[ 11.005292] BUG: KASAN: slab-out-of-bounds in tlv_data_is_valid+0x87/0xe0
[ 11.005984] Read of size 1 at addr ffff888002c695b0 by task mgmt-tester/87
[ 11.006711]
[ 11.007176]
[ 11.007429] Allocated by task 87:
[ 11.008151]
[ 11.008438] The buggy address belongs to the object at ffff888002c69580
[ 11.008438] which belongs to the cache kmalloc-64 of size 64
[ 11.010526] The buggy address is located 48 bytes inside of
[ 11.010526] 64-byte region [ffff888002c69580, ffff888002c695c0)
[ 11.012423] The buggy address belongs to the page:
[ 11.013291]
[ 11.013544] Memory state around the buggy address:
[ 11.014359] ffff888002c69480: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 11.015453] ffff888002c69500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 11.016232] >ffff888002c69580: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
[ 11.017010] ^
[ 11.017547] ffff888002c69600: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
[ 11.018296] ffff888002c69680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 11.019116] ==================================================================

Fixes: 2bb36870e8cb2 ("Bluetooth: Unify advertising instance flags check")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/mgmt.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 5340b1097afb..e9a4f11278d9 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -6468,6 +6468,9 @@ static bool tlv_data_is_valid(struct hci_dev *hdev, u32 adv_flags, u8 *data,
for (i = 0, cur_len = 0; i < len; i += (cur_len + 1)) {
cur_len = data[i];

+ if (!cur_len)
+ continue;
+
if (data[i + 1] == EIR_FLAGS &&
(!is_adv_data || flags_managed(adv_flags)))
return false;
--
2.30.2