From: Jason A. Donenfeld Date: Sat, 10 Jun 2017 02:59:07 +0000 (+0200) Subject: sunrpc: use constant time memory comparison for mac X-Git-Tag: v3.16.49~80 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=269bed5aa035e4e38fe91ba6502c3d908f6ffae6;p=linux sunrpc: use constant time memory comparison for mac commit 15a8b93fd5690de017ce665382ea45e5d61811a4 upstream. Otherwise, we enable a MAC forgery via timing attack. Signed-off-by: Jason A. Donenfeld Cc: "J. Bruce Fields" Cc: Jeff Layton Cc: Trond Myklebust Cc: Anna Schumaker Cc: linux-nfs@vger.kernel.org Signed-off-by: Anna Schumaker [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c index 0f43e894bc0a..4ff1a3486937 100644 --- a/net/sunrpc/auth_gss/gss_krb5_crypto.c +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -34,6 +34,7 @@ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ +#include #include #include #include @@ -838,7 +839,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf, if (ret) goto out_err; - if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) { + if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) { ret = GSS_S_BAD_SIG; goto out_err; }