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 8229329B77E for ; Wed, 9 Sep 2026 00:52:04 +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=1788915125; cv=none; b=hdVEaLdrYVWgrsus/cM5cBrXxiB0I1cW3ia21E8+O+xTBzw+j1j5RabTN3M735lsQhntWnCEuno5ccCBuJux13OVIw0D0ZchgERCZd537lTMW1RTm6oThBP800YHnN6TFMVXfAm7ABTbU7saoL0x+8xVyStpQFGoFK0nWrzxagA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788915125; c=relaxed/simple; bh=PPUicMYlmx5BRS3/NZjOXiP7oi3GPLx+/p/OttojhuM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qoOMUvffkrHkqzo3YQAIw/40oBSPOvz0Te+Nt9xc/g6Ha23AGsdLQZLOykH0/CB7VXtypA0Kazcq3JrHvOrkadB9Fn8u0Yo0AU+cgd2WaQEdLC2UQ4BVHJLtaDmoZAud+TZoAVNw/r9bOASdkAWJpIAb9hAJnHUtgoG/b/XVXeg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GFtf3qrL; 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="GFtf3qrL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D60DD1F00A3A; Wed, 9 Sep 2026 00:52:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788915124; bh=B1VTfR1jn4ORUMe2JedriWle9vcnW9hlWdZNDRIdO5M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GFtf3qrLBjO9erE88PQnyIk9j4uDFTK0kUBnymC7ACTgLP+RRQayGIvCbJN84CPWe uluEfFGf3BF4CrfGqP9p70rFHsBDgR34anVH+qFDbWwjMZ7Vqe5GDNUwWE6k76swog UhEkZSYijsRPkF/eiZ+svaH01uxJk3b2TrGbYC+yQ+wyoj3c0UA746Bu0l1RsJ2NzH K7YsbXJOGc5DZsy8CIWjkfjGZGY+fI/HqI5wpjgdgD5lInUQULTF+lKvbbGY6fe/Pi 7UJK7Zsgl2T08ZDmfjidjr+d3rl4kOkb31EWpOnIr+43NE6ImgzGXhV3R8fgGeJyjr T6d/oJEbURcwg== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Sasha Levin Subject: [PATCH 6.18.y 2/2] svcrdma: Reject Read lists that exceed the page budget Date: Tue, 8 Sep 2026 20:52:01 -0400 Message-ID: <20260909005201.804311-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909005201.804311-1-sashal@kernel.org> References: <2026090330-audacity-nutcase-5491@gregkh> <20260909005201.804311-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 0ca487abb3bdf581851664b5db21f364caf57682 ] Individual Read segment lengths are validated at decode time, but nothing prevents a requester from sending multiple segments whose cumulative length exceeds the rq_pages array budget. When one segment fills the page array exactly, the runtime guard in svc_rdma_build_read_segment() is bypassed because len reaches zero. A subsequent segment then accesses the NULL sentinel slot at rq_pages[rq_maxpages], resulting in a NULL pointer dereference during DMA mapping. Accumulate pages across all Read segments and reject the message at decode time when the total would overflow the page budget. Fixes: 026d958b38c6 ("svcrdma: Add recvfrom helpers to svc_rdma_rw.c") Cc: stable@vger.kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 30157636288eb..1075bfd9fed61 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -430,11 +430,14 @@ static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, * to the first byte past the Read list. rc_read_pcl and * rc_call_pcl cl_count fields are set to the number of * Read segments in the list. - * %false: Read list is corrupt. @rctxt's xdr_stream is left in an - * unknown state. + * %false: Read list is corrupt or exceeds the page budget. @rctxt's + * xdr_stream is left in an unknown state. */ static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) { + unsigned int maxlen = rctxt->rc_maxpages << PAGE_SHIFT; + unsigned int total_len = 0; + rctxt->rc_call_pcl.cl_count = 0; rctxt->rc_read_pcl.cl_count = 0; while (xdr_item_is_present(p)) { @@ -448,7 +451,10 @@ static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) xdr_decode_read_segment(p, &position, &handle, &length, &offset); - if (length > rctxt->rc_maxpages << PAGE_SHIFT) + if (length > maxlen) + return false; + total_len += length; + if (PAGE_ALIGN(total_len) > maxlen) return false; if (position) { if (position & 3) -- 2.53.0