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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <6a19f098.abb04025.19af7b.0003.GAE@google.com> References: <6a19f098.abb04025.19af7b.0003.GAE@google.com> To: syzbot Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netfs@lists.linux.dev, pc@manguebit.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [netfs?] KASAN: slab-use-after-free Read in netfs_unbuffered_write Precedence: bulk X-Mailing-List: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Thu, 25 Jun 2026 13:50:57 +0100 Message-ID: <3106406.1782391857@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: jJh_Vf29cEhMmt1Vow-NczHC7J1akdK26ldklpbM4pc_1782391860 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-ID: <3106405.1782391857.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git= 8fde5d1d47f6 diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index 25f8ceb15fad..c16fbad286a1 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -166,13 +166,16 @@ static int netfs_unbuffered_write(struct netfs_io_req= uest *wreq) =09=09 */ =09=09subreq->error =3D -EAGAIN; =09=09trace_netfs_sreq(subreq, netfs_sreq_trace_retry); -=09=09if (subreq->transferred > 0) +=09=09if (subreq->transferred > 0) { =09=09=09iov_iter_advance(&wreq->buffer.iter, subreq->transferred); +=09=09=09wreq->transferred +=3D subreq->transferred; +=09=09} =20 =09=09if (stream->source =3D=3D NETFS_UPLOAD_TO_SERVER && =09=09 wreq->netfs_ops->retry_request) =09=09=09wreq->netfs_ops->retry_request(wreq, stream); =20 +=09=09__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags); =09=09__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags); =09=09__clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags); =09=09__clear_bit(NETFS_SREQ_FAILED, &subreq->flags); @@ -186,17 +189,10 @@ static int netfs_unbuffered_write(struct netfs_io_req= uest *wreq) =20 =09=09netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); =20 -=09=09if (stream->prepare_write) { +=09=09if (stream->prepare_write) =09=09=09stream->prepare_write(subreq); -=09=09=09__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); -=09=09=09netfs_stat(&netfs_n_wh_retry_write_subreq); -=09=09} else { -=09=09=09struct iov_iter source; - -=09=09=09netfs_reset_iter(subreq); -=09=09=09source =3D subreq->io_iter; -=09=09=09netfs_reissue_write(stream, subreq, &source); -=09=09} +=09=09__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); +=09=09netfs_stat(&netfs_n_wh_retry_write_subreq); =09} =20 =09netfs_unbuffered_write_done(wreq);