CVE-2026-90187null_blk: free zones array on device power-off

Official description

In the Linux kernel, the following vulnerability has been resolved: null_blk: free zones array on device power-off null_init_zoned_dev() allocates dev->zones when a zoned device is powered on, but null_del_dev() never frees it on power-off; dev->zones is only freed later in null_free_dev(), when the configfs directory is removed. If the device is powered off and then on again, null_init_zoned_dev() allocates a new array and overwrites the dev->zones pointer, leaking the previous allocation each power cycle. Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it. And calling null_free_zoned_dev() in null_free_dev() is no longer necessary because every caller already invokes null_del_dev() first: via nullb_group_drop_item() before nullb_device_release(), in the null_add_dev() error path of null_create_dev(), and in null_destroy_dev(). Remove the redundant call. And take &lock around zone_cond_store() in the two store wrappers to serialize dev->zones check-and-deref against its alloc/free, which already run under &lock. The reason there was no problem before is that only nullb_device_release() or null_exit() frees the dev->zones, which guarantees that subsequent users won't access the configfs interface.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/26d21585caa61c30d0f3044a1e6d172456148c9f
• https://git.kernel.org/stable/c/08a31a2cc3d1cea67ccd292d01511cd0a72d4656
• https://git.kernel.org/stable/c/056be41932c95aabdb3c2967d1ef4978f17a0225
• https://git.kernel.org/stable/c/b2437d37fcc31fce8a5da1cc1739e284814d2491
• https://git.kernel.org/stable/c/0a3afab87124171022fb3579502fa38ef5b311c9
• https://git.kernel.org/stable/c/2a6357a9b935a34f5508618fee8a7fffbf7722a8