From 053baab47d17b769e4feb7d5216df36dc5f057a6 Mon Sep 17 00:00:00 2001 From: Thomas Huth Date: Fri, 7 Aug 2026 14:58:41 +0200 Subject: [PATCH] Bluetooth: SMP: clear the aes_cmac_key when done Clear the local aes_cmac_key structure via __cleanup() function when we're done with it to avoid that sensitive data could leak on the stack. While we're at it, also clear the tmp[] array here that is populated with a raw version of the original key and thus would leak the same information via the stack otherwise. Signed-off-by: Thomas Huth Link: https://patch.msgid.link/20260807125845.1477067-5-thuth@redhat.com Signed-off-by: Eric Biggers --- net/bluetooth/smp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index c4470958b0d5..4a32e4f80b48 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -164,7 +164,7 @@ static inline void swap_buf(const u8 *src, u8 *dst, size_t len) static int smp_aes_cmac(const u8 k[16], const u8 *m, size_t len, u8 mac[16]) { uint8_t tmp[16], mac_msb[16], msg_msb[CMAC_MSG_MAX]; - struct aes_cmac_key key; + struct aes_cmac_key key __cleanup(aes_cmac_zeroize_key); int err; if (len > CMAC_MSG_MAX) @@ -178,6 +178,7 @@ static int smp_aes_cmac(const u8 k[16], const u8 *m, size_t len, u8 mac[16]) SMP_DBG("key %16phN", k); err = aes_cmac_preparekey(&key, tmp, 16); + memzero_explicit(tmp, sizeof(tmp)); if (WARN_ON_ONCE(err)) /* Should never happen, as 16 is valid keylen */ return err; aes_cmac(&key, msg_msb, len, mac_msb);