From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D4104B66FC for ; Thu, 3 Sep 2026 14:30:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445821; cv=none; b=tpHb9TjogOUcqNyCk47HShQmgD+0xXX52QAPObQqatYSvCJE0UT1fSlX35ZSdSG0bHS5W23yhItxuLRnks/icr1etqPZCnTRdop1UzmuKXIixY0BW+XTV0eTgXJt7WjwpEivm4zPGK8xbE9eBh/vXXuhH5fBj/gSG8uO//gcwWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445821; c=relaxed/simple; bh=JJYv3tmVLMOtA+1Am7QJ0uyaPutKCkXeQjL8uwm31zA=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=Iz4/vuscyi9NAyhP+Qi1EYP78TrdN91W8QDaRQZJ+RrSHaR5frLmC3wgyQT+65086nsOphFP98cznLazvp92zIN+fSEHGdY/VYIfIIfNN2UA+xG0XOa6Z3bQ5K9Wl9JJ/u4zHJBkeXUfC5zeyP8X3O2vH8FZIpZjnX4PLabp/p4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=deD3+apj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="deD3+apj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A8581F00ACF; Thu, 3 Sep 2026 14:30:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788445801; bh=NwIMoS5qxA8paXaeGMn1UoBctoIHYgwzA2HDXUyOLRc=; h=Subject:To:Cc:From:Date; b=deD3+apj/7q5Sk/gduzYlhPROAJ73lG5Z9hUHm8agOPy7ohTvJLOIuLkPKLfHvSMl 7y9PaUNPK6TGTNld4V+m2vleVcwEmSAo+ruv3zVn6JOTLZ5kHaMW4vBaJvPeBYutuD joDKqVsr9MUntrPuWx7EocsDFy0SXzD3pubVmR7U= Subject: FAILED: patch "[PATCH] SUNRPC: svcauth_gss: enforce krb5 token minimum length" failed to apply to 5.10-stable tree To: clm@meta.com,chuck.lever@oracle.com,jlayton@kernel.org Cc: From: Date: Thu, 03 Sep 2026 16:05:53 +0200 Message-ID: <2026090353-ogle-atop-5025@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x a919c5c88769cf8fb3ec071e6078d830bf512489 # git commit -s git send-email --to '' --in-reply-to '2026090353-ogle-atop-5025@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a919c5c88769cf8fb3ec071e6078d830bf512489 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Sat, 23 May 2026 21:02:10 -0400 Subject: [PATCH] SUNRPC: svcauth_gss: enforce krb5 token minimum length svcauth_gss_unwrap_priv() validates only an upper bound on the wire-supplied opaque length before handing the buffer to gss_unwrap(): if (len > xdr_stream_remaining(xdr)) goto unwrap_failed; offset = xdr_stream_pos(xdr); ... maj_stat = gss_unwrap(ctx, offset, offset + len, buf); The wire value `len` flows unchanged as the upper bound into the krb5 unwrap path, so a len in [0, 16] passes this check and is handed to gss_unwrap(). For a krb5 v2 context that lands in gss_krb5_unwrap_v2(), which reads the 16-byte RFC 4121 token header fields at ptr+4 and ptr+6 and then calls rotate_left() before any integrity check. With a sub-header length the header reads run past the token, and _rotate_left()'s `shift %= buf->len` path can divide by zero when buf->len has been driven to zero by the truncated token. A header-only token (len == 16) is equally invalid: with a non-zero RRC field and the opaque blob ending at the XDR buffer boundary, rotate_left() builds a zero-length subbuffer, reaching the same division. Reject the token at the server entry point before it reaches the krb5 unwrap core. A valid sealed RFC 4121 token must contain the 16-byte header plus at least some encrypted payload. Fix by adding a minimum-length check immediately after the existing upper-bound check: if (len <= GSS_KRB5_TOK_HDR_LEN) goto unwrap_failed; Fixes: 7c9fdcfb1b64 ("[PATCH] knfsd: svcrpc: gss: server-side implementation of rpcsec_gss privacy") Cc: stable@vger.kernel.org Assisted-by: kres (claude-opus-4-7) Signed-off-by: Chris Mason Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260524010213.557424-2-cel@kernel.org Signed-off-by: Chuck Lever diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index d14209031e18..8e8aceb31270 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -949,6 +949,8 @@ svcauth_gss_unwrap_priv(struct svc_rqst *rqstp, u32 seq, struct gss_ctx *ctx) } if (len > xdr_stream_remaining(xdr)) goto unwrap_failed; + if (len <= GSS_KRB5_TOK_HDR_LEN) + goto unwrap_failed; offset = xdr_stream_pos(xdr); saved_len = buf->len;