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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: Steve French , Christian Brauner cc: dhowells@redhat.com, kernel test robot , Jeff Layton , Paulo Alcantara , linux-cifs@vger.kernel.org, netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] cifs: Fix reversion of the iter in cifs_readv_receive(). Precedence: bulk X-Mailing-List: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2280666.1726594254.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Tue, 17 Sep 2024 18:30:54 +0100 Message-ID: <2280667.1726594254@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 cifs_read_iter_from_socket() copies the iterator that's passed in for the socket to modify as and if it will, and then advances the original iterato= r by the amount sent. However, both callers revert the advancement (althoug= h receive_encrypted_read() zeros beyond the iterator first). The problem is= , though, that cifs_readv_receive() reverts by the original length, not the amount transmitted which can cause an oops in iov_iter_revert(). Fix this by: (1) Remove the iov_iter_advance() from cifs_read_iter_from_socket(). (2) Remove the iov_iter_revert() from both callers. This fixes the bug i= n cifs_readv_receive(). (3) In receive_encrypted_read(), if we didn't get back as much data as th= e buffer will hold, copy the iterator, advance the copy and use the cop= y to drive iov_iter_zero(). As a bonus, this gets rid of some unnecessary processing. This was triggered by generic/074 with the "-o sign" mount option. Fixes: 3ee1a1fc3981 ("cifs: Cut over to using netfslib") Signed-off-by: David Howells cc: Steve French cc: Paulo Alcantara cc: Shyam Prasad N cc: Rohith Surabattula cc: Jeff Layton cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/smb/client/connect.c | 6 +----- fs/smb/client/smb2ops.c | 9 ++++++--- fs/smb/client/transport.c | 3 --- 3 files changed, 7 insertions(+), 11 deletions(-) diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index 5375b0c1dfb9..06c16b0ce3e8 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -811,13 +811,9 @@ cifs_read_iter_from_socket(struct TCP_Server_Info *se= rver, struct iov_iter *iter unsigned int to_read) { struct msghdr smb_msg =3D { .msg_iter =3D *iter }; - int ret; = iov_iter_truncate(&smb_msg.msg_iter, to_read); - ret =3D cifs_readv_from_socket(server, &smb_msg); - if (ret > 0) - iov_iter_advance(iter, ret); - return ret; + return cifs_readv_from_socket(server, &smb_msg); } = static bool diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index 159a063de6dd..5550d5237b22 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -4869,9 +4869,12 @@ receive_encrypted_read(struct TCP_Server_Info *serv= er, struct mid_q_entry **mid, goto discard_data; = server->total_read +=3D rc; - if (rc < len) - iov_iter_zero(len - rc, &iter); - iov_iter_revert(&iter, len); + if (rc < len) { + struct iov_iter tmp =3D iter; + + iov_iter_advance(&tmp, rc); + iov_iter_zero(len - rc, &tmp); + } iov_iter_truncate(&iter, dw->len); = rc =3D cifs_discard_remaining_data(server); diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c index 6e68aaf5bd20..abf966f6ff0a 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -1813,11 +1813,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, = struct mid_q_entry *mid) length =3D data_len; /* An RDMA read is already done. */ else #endif - { length =3D cifs_read_iter_from_socket(server, &rdata->subreq.io_iter, data_len); - iov_iter_revert(&rdata->subreq.io_iter, data_len); - } if (length > 0) rdata->got_bytes +=3D length; server->total_read +=3D length;