4.19-stable review patch. If anyone has any objections, please let me know.
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From: Luiz Augusto von Dentz luiz.von.dentz@intel.com
[ Upstream commit b541260615f601ae1b5d6d0cc54e790de706303b ]
memcmp is not consider safe to use with cryptographic secrets:
'Do not use memcmp() to compare security critical data, such as cryptographic secrets, because the required CPU time depends on the number of equal bytes.'
While usage of memcmp for ZERO_KEY may not be considered a security critical data, it can lead to more usage of memcmp with pairing keys which could introduce more security problems.
Fixes: 455c2ff0a558 ("Bluetooth: Fix BR/EDR out-of-band pairing with only initiator data") Fixes: 33155c4aae52 ("Bluetooth: hci_event: Ignore NULL link key") Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/hci_event.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 843502783b268..8b59f7808628a 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -25,6 +25,8 @@ /* Bluetooth HCI event handling. */
#include <asm/unaligned.h> +#include <linux/crypto.h> +#include <crypto/algapi.h>
#include <net/bluetooth/bluetooth.h> #include <net/bluetooth/hci_core.h> @@ -3827,7 +3829,7 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, struct sk_buff *skb) goto unlock;
/* Ignore NULL link key against CVE-2020-26555 */ - if (!memcmp(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) { + if (!crypto_memneq(ev->link_key, ZERO_KEY, HCI_LINK_KEY_SIZE)) { bt_dev_dbg(hdev, "Ignore NULL link key (ZERO KEY) for %pMR", &ev->bdaddr); hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE); @@ -4313,8 +4315,8 @@ static u8 bredr_oob_data_present(struct hci_conn *conn) * available, then do not declare that OOB data is * present. */ - if (!memcmp(data->rand256, ZERO_KEY, 16) || - !memcmp(data->hash256, ZERO_KEY, 16)) + if (!crypto_memneq(data->rand256, ZERO_KEY, 16) || + !crypto_memneq(data->hash256, ZERO_KEY, 16)) return 0x00;
return 0x02; @@ -4324,8 +4326,8 @@ static u8 bredr_oob_data_present(struct hci_conn *conn) * not supported by the hardware, then check that if * P-192 data values are present. */ - if (!memcmp(data->rand192, ZERO_KEY, 16) || - !memcmp(data->hash192, ZERO_KEY, 16)) + if (!crypto_memneq(data->rand192, ZERO_KEY, 16) || + !crypto_memneq(data->hash192, ZERO_KEY, 16)) return 0x00;
return 0x01;