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 6BDED3EE1DD; Wed, 27 May 2026 15:20:02 +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=1779895203; cv=none; b=Wth6gvC33uDdnF3GhNaBMGSpqy29HiND/+MFcf7O3JUqyCFW846ilPzfSk3mLcxjP/cF9jpMs38Ij7Qj5bZsNUWiZmM1/n3DlQEKyZu5+4mHl4xQ+hqB/VA02B1dmOsBcio0UwCTPrKbWyx7H5SpsMGH4SUEnenZBaBlfGmhsCo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779895203; c=relaxed/simple; bh=hYecvyfRrezkLa4t2+80NwKEumG5oOhUXVJYxt/SHRo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=AQgK6IeigrNXZapQf+bDOKbuaLn5pMv0v8XRvxCiN6rC9TzZS4QRn/bPtB2s8cfUcjcYCuIa1x22JXkDKnXuud9S1d6AACU8n5ZCThEoCUMCLqcodTLO5EYTN8P7nLEfXNok31a+prJMImkQZP5BU/wFD7P1Tx+PiE1/RpJl+ms= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a2A3RCU+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="a2A3RCU+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48ACD1F000E9; Wed, 27 May 2026 15:20:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779895202; bh=C1TnMaxlD9w4quSPJUdsEFhxSc/xkf2fPPBYXY5T6/Q=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=a2A3RCU+z3k6YbP98HfYAD5h9E3u/6C6e77Lql4sPFtfzA2QcX6IZczSwSG7KLUsB wpUv4HLADXfE68wnUHI5nqQMeGMYTGzfA0N1FoII2PrmQJVJI70u4f8p95SAEWU9Ft qUh8OchX/UZ7oVhSa4X2/6T/R3P+BL/FzC4ID429w8k8BXRISA04q2icykG64rCgxQ Hi6V/by6mfgbMa0bAilpoyNwMo94c936vEIV5e30SN2kvZmz6UMQiqzp3zkO1jTUGV ixNoz/y9mETxkKVV5evSLztJ1ZXgROyyLi1e6GjTylBi3B5E77ehbTUYXurv37CoF7 qgWBVPMTcEhNw== Message-ID: Subject: Re: [PATCH 0/6] svcrdma: harden parsed chunk list against malformed wire values From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org, Chuck Lever , Chris Mason Date: Wed, 27 May 2026 11:19:59 -0400 In-Reply-To: <20260526-rpc-kernel-bugs-v1-0-e251306ccca9@oracle.com> References: <20260526-rpc-kernel-bugs-v1-0-e251306ccca9@oracle.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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stores wire-supplied chunk positions, lengths, > and segment counts verbatim in the parsed chunk list. Consumer > functions compute gap lengths and sub-range offsets from these values > using unsigned subtraction. A malicious or buggy peer can supply > values that cause these subtractions to underflow, exposing slab > memory to the Reply channel or driving oversized allocations. >=20 > The fix proceeds in two layers. Consumer functions in svc_rdma_rw.c > gain bounds checks against the saved inline body length before each > unsigned subtraction, closing the immediate underflow paths. The > Read list decoder in svc_rdma_recvfrom.c gains a segment-length cap > against the receive context's page budget, and the existing page- > overrun guard in svc_rdma_build_read_segment() is corrected to > release the rw context it has already acquired. These consumer-side > fixes are backportable independently. >=20 > pcl_for_each_segment() uses an inclusive upper bound that underflows > when ch_segcount is zero, turning a zero-segment Write or Reply > chunk into an unbounded memory walk. The macro is changed to a > half-open bound that naturally produces an empty iteration for > ch_segcount =3D=3D 0. The decoder then also rejects zero-segment chunks > at the wire boundary, and reorders pcl_alloc_write() so that only > fully-populated chunks appear on the list. The macro fix remains as > defense in depth and is safe to backport to trees without the decoder > change. >=20 > A consolidation pass validates Read chunk positions and overlap > invariants once, immediately after decoding, so that future PCL > consumers inherit the guarantee without replicating per-site checks. >=20 > --- > Chris Mason (3): > svcrdma: Fix offset arithmetic in read_chunk_range > svcrdma: fix pcl_for_each_segment for empty chunks > svcrdma: reject Write/Reply chunks with segcount 0 >=20 > Chuck Lever (3): > svcrdma: validate Read chunk positions before reconstruction > svcrdma: reject oversized Read segments at decode time > svcrdma: Validate Read chunk positions at decode time >=20 > include/linux/sunrpc/svc_rdma_pcl.h | 4 ++- > net/sunrpc/xprtrdma/svc_rdma_pcl.c | 63 +++++++++++++++++++++++++++= +++--- > net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 14 ++++++-- > net/sunrpc/xprtrdma/svc_rdma_rw.c | 52 ++++++++++++++++++++------- > 4 files changed, 113 insertions(+), 20 deletions(-) > --- > base-commit: 887d478bb2115cec0be8caae58bad4d4b3109b1a > change-id: 20260524-rpc-kernel-bugs-fb537a0615ec >=20 > Best regards, > -- =20 > Chuck Lever Acked-by: Jeff Layton