From: Eric Biggers <ebiggers@kernel.org>
commit a458b2902115b26a25d67393b12ddd57d1216aaa upstream.
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>
Reviewed-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Link: https://patch.msgid.link/20250818202724.15713-1-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[Andrey Troshin: backport fix for 5.10]
Signed-off-by: Andrey Troshin <drtrosh@yandex-team.ru>
---
Backport fix for CVE-2025-39702
Link: https://nvd.nist.gov/vuln/detail/CVE-2025-39702
---
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 4a3f7bb027ed..8bb7f94cba1e 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -35,6 +35,7 @@
#include <net/xfrm.h>
#include <crypto/hash.h>
+#include <crypto/algapi.h>
#include <crypto/sha.h>
#include <net/seg6.h>
#include <net/genetlink.h>
@@ -270,7 +271,7 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
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;
--
2.34.1