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(59-115-195-252.dynamic-ip.hinet.net. [59.115.195.252]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82cf9ca4efesm21916840b3a.61.2026.04.08.09.14.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 09:14:41 -0700 (PDT) From: Sean Chang To: trondmy@kernel.org, anna@kernel.org Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Chang Subject: [PATCH v1 1/2] NFS: fix RCU safety in nfs_compare_super_address Date: Thu, 9 Apr 2026 00:14:27 +0800 Message-Id: <20260408161428.155169-2-seanwascoding@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260408161428.155169-1-seanwascoding@gmail.com> References: <20260408161428.155169-1-seanwascoding@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The cl_xprt pointer in struct rpc_clnt is marked as __rcu. Accessing it directly in nfs_compare_super_address() without RCU protection is unsafe and triggers Sparse warnings about dereferencing noderef expressions. Fix this by wrapping the access with rcu_read_lock() and using rcu_dereference() to safely retrieve the transport pointer. This ensures the xprt remains valid during the comparison of network namespaces and addresses, preventing potential use-after-free during concurrent transport updates. Signed-off-by: Sean Chang --- fs/nfs/super.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 7a318581f85b..071337f9ea37 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -1166,43 +1166,55 @@ static int nfs_set_super(struct super_block *s, str= uct fs_context *fc) static int nfs_compare_super_address(struct nfs_server *server1, struct nfs_server *server2) { + struct rpc_xprt *xprt1, *xprt2; struct sockaddr *sap1, *sap2; - struct rpc_xprt *xprt1 =3D server1->client->cl_xprt; - struct rpc_xprt *xprt2 =3D server2->client->cl_xprt; + int ret =3D 0; + + rcu_read_lock(); + + xprt1 =3D rcu_dereference(server1->client->cl_xprt); + xprt2 =3D rcu_dereference(server2->client->cl_xprt); + + if (!xprt1 || !xprt2) + goto out; =20 if (!net_eq(xprt1->xprt_net, xprt2->xprt_net)) - return 0; + goto out; =20 sap1 =3D (struct sockaddr *)&server1->nfs_client->cl_addr; sap2 =3D (struct sockaddr *)&server2->nfs_client->cl_addr; =20 if (sap1->sa_family !=3D sap2->sa_family) - return 0; + goto out; =20 switch (sap1->sa_family) { case AF_INET: { struct sockaddr_in *sin1 =3D (struct sockaddr_in *)sap1; struct sockaddr_in *sin2 =3D (struct sockaddr_in *)sap2; if (sin1->sin_addr.s_addr !=3D sin2->sin_addr.s_addr) - return 0; + goto out; if (sin1->sin_port !=3D sin2->sin_port) - return 0; + goto out; break; } case AF_INET6: { struct sockaddr_in6 *sin1 =3D (struct sockaddr_in6 *)sap1; struct sockaddr_in6 *sin2 =3D (struct sockaddr_in6 *)sap2; if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr)) - return 0; + goto out; if (sin1->sin6_port !=3D sin2->sin6_port) - return 0; + goto out; break; } default: - return 0; + goto out; } =20 - return 1; + ret =3D 1; + +out: + rcu_read_unlock(); + return ret; } =20 static int nfs_compare_userns(const struct nfs_server *old, --=20 2.34.1 From nobody Mon Jun 15 06:35:45 2026 Received: from mail-pf1-f173.google.com (mail-pf1-f173.google.com [209.85.210.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A03BB34C83C for ; 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(59-115-195-252.dynamic-ip.hinet.net. [59.115.195.252]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82cf9ca4efesm21916840b3a.61.2026.04.08.09.14.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 09:14:43 -0700 (PDT) From: Sean Chang To: trondmy@kernel.org, anna@kernel.org Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Chang Subject: [PATCH v1 2/2] NFS: use unsigned long for req field in nfs_page_class Date: Thu, 9 Apr 2026 00:14:28 +0800 Message-Id: <20260408161428.155169-3-seanwascoding@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260408161428.155169-1-seanwascoding@gmail.com> References: <20260408161428.155169-1-seanwascoding@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The nfs_page_class tracepoint used a pointer for the req field. This caused Sparse to complain about dereferencing a pointer marked as __private within the trace ring buffer context. Change the field type to unsigned long to store the address of the request without dereferencing it. Update TP_printk to use 0x%lx for consistent hexadecimal output, allowing for unique identification of requests across the trace log. Signed-off-by: Sean Chang --- fs/nfs/nfstrace.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h index 9f9ce4a565ea..4150bbd99cfa 100644 --- a/fs/nfs/nfstrace.h +++ b/fs/nfs/nfstrace.h @@ -1496,7 +1496,7 @@ DECLARE_EVENT_CLASS(nfs_page_class, __field(dev_t, dev) __field(u32, fhandle) __field(u64, fileid) - __field(const struct nfs_page *__private, req) + __field(unsigned long, req) __field(loff_t, offset) __field(unsigned int, count) __field(unsigned long, flags) @@ -1509,14 +1509,14 @@ DECLARE_EVENT_CLASS(nfs_page_class, __entry->dev =3D inode->i_sb->s_dev; __entry->fileid =3D nfsi->fileid; __entry->fhandle =3D nfs_fhandle_hash(&nfsi->fh); - __entry->req =3D req; + __entry->req =3D (unsigned long)req; __entry->offset =3D req_offset(req); __entry->count =3D req->wb_bytes; __entry->flags =3D req->wb_flags; ), =20 TP_printk( - "fileid=3D%02x:%02x:%llu fhandle=3D0x%08x req=3D%p offset=3D%lld count= =3D%u flags=3D%s", + "fileid=3D%02x:%02x:%llu fhandle=3D0x%08x req=3D0x%lx offset=3D%lld cou= nt=3D%u flags=3D%s", MAJOR(__entry->dev), MINOR(__entry->dev), (unsigned long long)__entry->fileid, __entry->fhandle, __entry->req, __entry->offset, __entry->count, --=20 2.34.1