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Bluetooth: hci_sock: Correctly bounds check and pad HCI_MON_NEW_INDEX name

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commit cb3871b1cd135a6662b732fbc6b3db4afcdb4a64 upstream.

The code pattern of memcpy(dst, src, strlen(src)) is almost always
wrong. In this case it is wrong because it leaves memory uninitialized
if it is less than sizeof(ni->name), and overflows ni->name when longer.

Normally strtomem_pad() could be used here, but since ni->name is a
trailing array in struct hci_mon_new_index, compilers that don't support
-fstrict-flex-arrays=3 can't tell how large this array is via
__builtin_object_size(). Instead, open-code the helper and use sizeof()
since it will work correctly.

Additionally mark ni->name as __nonstring since it appears to not be a
%NUL terminated C string.

Cc: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Cc: Edward AD <twuufnxlz@gmail.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-bluetooth@vger.kernel.org
Cc: netdev@vger.kernel.org
Fixes: 18f547f3fc07 ("Bluetooth: hci_sock: fix slab oob read in create_monitor_event")
Link: https://lore.kernel.org/lkml/202310110908.F2639D3276@keescook/
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kees Cook 2023-10-11 09:31:44 -07:00 committed by Greg Kroah-Hartman
parent 4d161e18b1
commit b849a38e18
2 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/bluetooth/hci_mon.h
View File

@ -54,7 +54,7 @@ struct hci_mon_new_index {
__u8 type;
__u8 bus;
bdaddr_t bdaddr;
char name[8];
char name[8] __nonstring;
} __packed;
#define HCI_MON_NEW_INDEX_SIZE 16

3
net/bluetooth/hci_sock.c
View File

@ -430,7 +430,8 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)
ni->type = hdev->dev_type;
ni->bus = hdev->bus;
bacpy(&ni->bdaddr, &hdev->bdaddr);
memcpy(ni->name, hdev->name, strlen(hdev->name));
memcpy_and_pad(ni->name, sizeof(ni->name), hdev->name,
strnlen(hdev->name, sizeof(ni->name)), '\0');
opcode = cpu_to_le16(HCI_MON_NEW_INDEX);
break;