[PATCH net v2] ipv6: sr: Fix MAC comparison to be constant-time
From: Eric Biggers <ebiggers@kernel.org>
Date: 2025-08-18 20:28:47
Also in:
linux-crypto, stable
Subsystem:
networking [general], networking [srv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Andrea Mayer, Linus Torvalds
To prevent timing attacks, MACs need to be compared in constant time.
Use the appropriate helper function for this.
Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
v2: sent as standalone patch targeting net instead of net-next.
net/ipv6/seg6_hmac.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index f78ecb6ad8383..5dae892bbc73b 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c@@ -33,10 +33,11 @@ #include <net/ip6_route.h> #include <net/addrconf.h> #include <net/xfrm.h> #include <crypto/hash.h> +#include <crypto/utils.h> #include <net/seg6.h> #include <net/genetlink.h> #include <net/seg6_hmac.h> #include <linux/random.h>
@@ -278,11 +279,11 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb) return false; if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output)) return false; - if (memcmp(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN) != 0) + if (crypto_memneq(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN)) return false; return true; } EXPORT_SYMBOL(seg6_hmac_validate_skb);
base-commit: 715c7a36d59f54162a26fac1d1ed8dc087a24cf1 -- 2.50.1