The vblk->vqs releases during freeze. If resume fails before vblk->vqs is allocated, later freeze/remove may attempt to free vqs again. Set vblk->vqs to NULL after freeing to avoid double free.
Signed-off-by: Cong Zhang <[email protected]> --- The patch fixes a double free issue that occurs in virtio_blk during freeze/resume. The issue is caused by: 1. During the first freeze, vblk->vqs is freed but pointer is not set to NULL. 2. Virtio block device fails before vblk->vqs is allocated during resume. 3. During the next freeze, vblk->vqs gets freed again, causing the double free crash. --- drivers/block/virtio_blk.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index f061420dfb10c40b21765b173fab7046aa447506..746795066d7f56a01c9a9c0344d24f9fa06841eb 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -1026,8 +1026,13 @@ static int init_vq(struct virtio_blk *vblk) out: kfree(vqs); kfree(vqs_info); - if (err) + if (err) { kfree(vblk->vqs); + /* + * Set to NULL to prevent freeing vqs again during freezing. + */ + vblk->vqs = NULL; + } return err; } @@ -1598,6 +1603,12 @@ static int virtblk_freeze_priv(struct virtio_device *vdev) vdev->config->del_vqs(vdev); kfree(vblk->vqs); + /* + * Set to NULL to prevent freeing vqs again after a failed vqs + * allocation during resume. Note that kfree() already handles NULL + * pointers safely. + */ + vblk->vqs = NULL; return 0; } --- base-commit: 8e2755d7779a95dd61d8997ebce33ff8b1efd3fb change-id: 20250926-virtio_double_free-7ab880d82a17 Best regards, -- Cong Zhang <[email protected]>
