Patch "Bluetooth: hci_event: Fix using memcmp when comparing keys" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: hci_event: Fix using memcmp when comparing keys

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-hci_event-fix-using-memcmp-when-comparing-.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 25dd7a7ff6f5d73f23cf5383713b4173ada706cd
Author: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Date:   Thu Oct 5 13:59:59 2023 -0700

    Bluetooth: hci_event: Fix using memcmp when comparing keys
    
    [ 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@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 0fe01b543b185..f182a7d3e44cf 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>
@@ -3946,7 +3948,7 @@ 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);
@@ -4445,8 +4447,8 @@ 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;
@@ -4456,8 +4458,8 @@ 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;