In the Linux kernel, the following vulnerability has been resolved:
mtd: mtdswap: Avoid freeing registered blktrans device twice
In mtdswap_add_mtd(), debugfs setup failure after successful blktrans
registration can free mbd_dev twice.
add_mtd_blktrans_dev() initializes the blktrans device reference and
publishes the disk. Once that succeeds, del_mtd_blktrans_dev() tears the
disk down and drops the blktrans reference; when that reference reaches
zero, blktrans_dev_release() frees the mtd_blktrans_dev.
The debugfs failure path called del_mtd_blktrans_dev(mbd_dev), then fell
through the common cleanup label and called kfree(mbd_dev) again. Clear
the local pointer after deregistration so the common cleanup can still
release the mtdswap state without freeing the blktrans object twice.
This issue was found by a static analysis checker and confirmed by
manual source review.
