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 58F2630E835 for ; Thu, 3 Sep 2026 14:29:56 +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=1788445808; cv=none; b=LN8kpbg9QnqGL1+C1l4mKS3Ot6D+6m93bntw02D2HLOPkbP5TvdSKjBPfzLyOUWhucW+vPldmP8Ax/AcBrDRdbMCuTfwvmxozc9XnVoOwOzmBDQtFo0c/55OfUZecaPdP19274IfEWO9eZr9pd+ZTUzVds4MEnHOD2JACfT1b+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445808; c=relaxed/simple; bh=Ry+ETSU7keF14ul6c3PdxXp+T0lcebAU2jb1L8Bpn40=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=sUBU5JIRE7TBlO7MsQ06gsNLgUKOpmxLSlDbm2oxZ04kwSamkCUeo+eO03XnKXb/SFLFl0W96rH3HJTRdLHnmNMOmRs6qzU4A9M2FF5wIfE8DQxTctdwCf60ep00d/MAIQM/m7hA435CF15l2hDwBoIGkd8nnqHwIJ+iqFhCfG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QN87nW4z; 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="QN87nW4z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D1D81F000E9; Thu, 3 Sep 2026 14:29:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788445796; bh=OAUcETI2H8/U44VRVpSDAHcDFPADcn92N+Xaoj6lBTs=; h=Subject:To:Cc:From:Date; b=QN87nW4zOChA6DNUik7HIqe0H68xIQA55rgXY0b6L6W2GgKHebPPPaRqlmf7akDRm 51mtaF5SCXlUN8QFkpq+fYesHE/0h59tC7D2/+DrEYkHiUSX+hLLJXg/SCZ+xJET5z sWuWVJh3ONY1XYGk6F5/j0wdVbc+MPtGn4wljuG8= Subject: FAILED: patch "[PATCH] SUNRPC: svcauth_gss: enforce krb5 token minimum length" failed to apply to 5.15-stable tree To: clm@meta.com,chuck.lever@oracle.com,jlayton@kernel.org Cc: From: Date: Thu, 03 Sep 2026 16:05:52 +0200 Message-ID: <2026090352-bamboo-relic-6231@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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x a919c5c88769cf8fb3ec071e6078d830bf512489 # git commit -s git send-email --to '' --in-reply-to '2026090352-bamboo-relic-6231@gregkh' --subject-prefix 'PATCH 5.15.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;