5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook keescook@chromium.org
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 --- include/net/bluetooth/hci_mon.h | 2 +- net/bluetooth/hci_sock.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-)
--- a/include/net/bluetooth/hci_mon.h +++ b/include/net/bluetooth/hci_mon.h @@ -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
--- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -430,7 +430,8 @@ static struct sk_buff *create_monitor_ev 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;