In the Linux kernel, the following vulnerability has been resolved: scsi: target: tcmu: Fix possible page UAF tcmu_try_get_data_page() looks up pages under cmdr_lock, but it does not take refcount properly and just returns page pointer. When tcmu_try_get_data_page() returns, the returned page may have been freed by tcmu_blocks_release(). We need to get_page() under cmdr_lock to avoid concurrent tcmu_blocks_release().
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.