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    Subject[PATCH 5.19 080/365] virtio-blk: Avoid use-after-free on suspend/resume
    Date
    From: Shigeru Yoshida <syoshida@redhat.com>

    commit 8d12ec10292877751ee4463b11a63bd850bc09b5 upstream.

    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] <TASK>
    [ 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().

    Fixes: 4e0400525691 ("virtio-blk: support polling I/O")
    Cc: "Suwan Kim" <suwan.kim027@gmail.com>
    Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
    Message-Id: <20220810160948.959781-1-syoshida@redhat.com>
    Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    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,
    --
    2.37.2


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