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Tsirkin" To: Shigeru Yoshida Cc: jasowang@redhat.com, axboe@kernel.dk, pbonzini@redhat.com, stefanha@redhat.com, virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] virtio-blk: Avoid use-after-free on suspend/resume Message-ID: <20220810084053-mutt-send-email-mst@kernel.org> References: <20220731070951.196831-1-shigeru.yoshida@gmail.com> <20220810.204556.441522765735488771.shigeru.yoshida@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220810.204556.441522765735488771.shigeru.yoshida@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 10, 2022 at 08:45:56PM +0900, Shigeru Yoshida wrote: > ping? > > On Sun, 31 Jul 2022 16:09:51 +0900, Shigeru Yoshida wrote: > > hctx->user_data is set to vq in virtblk_init_hctx(). However, vq is > > freed on suspend and reallocated on resume. So, hctx->user_data is > > invalid after resume, and it will cause use-after-free accessing which > > will result in the kernel crash something like below: > > > > [ 22.428391] Call Trace: > > [ 22.428899] > > [ 22.429339] virtqueue_add_split+0x3eb/0x620 > > [ 22.430035] ? __blk_mq_alloc_requests+0x17f/0x2d0 > > [ 22.430789] ? kvm_clock_get_cycles+0x14/0x30 > > [ 22.431496] virtqueue_add_sgs+0xad/0xd0 > > [ 22.432108] virtblk_add_req+0xe8/0x150 > > [ 22.432692] virtio_queue_rqs+0xeb/0x210 > > [ 22.433330] blk_mq_flush_plug_list+0x1b8/0x280 > > [ 22.434059] __blk_flush_plug+0xe1/0x140 > > [ 22.434853] blk_finish_plug+0x20/0x40 > > [ 22.435512] read_pages+0x20a/0x2e0 > > [ 22.436063] ? folio_add_lru+0x62/0xa0 > > [ 22.436652] page_cache_ra_unbounded+0x112/0x160 > > [ 22.437365] filemap_get_pages+0xe1/0x5b0 > > [ 22.437964] ? context_to_sid+0x70/0x100 > > [ 22.438580] ? sidtab_context_to_sid+0x32/0x400 > > [ 22.439979] filemap_read+0xcd/0x3d0 > > [ 22.440917] xfs_file_buffered_read+0x4a/0xc0 > > [ 22.441984] xfs_file_read_iter+0x65/0xd0 > > [ 22.442970] __kernel_read+0x160/0x2e0 > > [ 22.443921] bprm_execve+0x21b/0x640 > > [ 22.444809] do_execveat_common.isra.0+0x1a8/0x220 > > [ 22.446008] __x64_sys_execve+0x2d/0x40 > > [ 22.446920] do_syscall_64+0x37/0x90 > > [ 22.447773] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > This patch fixes this issue by getting vq from vblk, and removes > > virtblk_init_hctx(). > > > > Signed-off-by: Shigeru Yoshida Fixes: 4e0400525691 ("virtio-blk: support polling I/O") Cc: "Suwan Kim" I assume? > > --- > > drivers/block/virtio_blk.c | 24 ++++++++++-------------- > > 1 file changed, 10 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > > index 6fc7850c2b0a..d756423e0059 100644 > > --- a/drivers/block/virtio_blk.c > > +++ b/drivers/block/virtio_blk.c > > @@ -101,6 +101,14 @@ static inline blk_status_t virtblk_result(struct virtblk_req *vbr) > > } > > } > > > > +static inline struct virtio_blk_vq *get_virtio_blk_vq(struct blk_mq_hw_ctx *hctx) > > +{ > > + struct virtio_blk *vblk = hctx->queue->queuedata; > > + struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num]; > > + > > + return vq; > > +} > > + > > static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr) > > { > > struct scatterlist hdr, status, *sgs[3]; > > @@ -416,7 +424,7 @@ static void virtio_queue_rqs(struct request **rqlist) > > struct request *requeue_list = NULL; > > > > rq_list_for_each_safe(rqlist, req, next) { > > - struct virtio_blk_vq *vq = req->mq_hctx->driver_data; > > + struct virtio_blk_vq *vq = get_virtio_blk_vq(req->mq_hctx); > > bool kick; > > > > if (!virtblk_prep_rq_batch(req)) { > > @@ -837,7 +845,7 @@ static void virtblk_complete_batch(struct io_comp_batch *iob) > > static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob) > > { > > struct virtio_blk *vblk = hctx->queue->queuedata; > > - struct virtio_blk_vq *vq = hctx->driver_data; > > + struct virtio_blk_vq *vq = get_virtio_blk_vq(hctx); > > struct virtblk_req *vbr; > > unsigned long flags; > > unsigned int len; > > @@ -862,22 +870,10 @@ static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob) > > return found; > > } > > > > -static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, > > - unsigned int hctx_idx) > > -{ > > - struct virtio_blk *vblk = data; > > - struct virtio_blk_vq *vq = &vblk->vqs[hctx_idx]; > > - > > - WARN_ON(vblk->tag_set.tags[hctx_idx] != hctx->tags); > > - hctx->driver_data = vq; > > - return 0; > > -} > > - > > static const struct blk_mq_ops virtio_mq_ops = { > > .queue_rq = virtio_queue_rq, > > .queue_rqs = virtio_queue_rqs, > > .commit_rqs = virtio_commit_rqs, > > - .init_hctx = virtblk_init_hctx, > > .complete = virtblk_request_done, > > .map_queues = virtblk_map_queues, > > .poll = virtblk_poll, > > -- > > 2.37.1 > >