UBUNTU-CVE-2026-53185: Use After Free

In the Linux kernel, the following vulnerability has been resolved: zram: fix use-after-free in zrambvecwritepartial() zramreadpage() picks the sync or async backing device read path based on whether the parent bio is NULL. zrambvecwritepartial() passes its parent bio down, so for ZRAMWB slots the read is dispatched asynchronously and zramreadpage() returns 0 while the bio is still in flight. The caller then runs memcpyfrombvec(), zramwritepage() and freepage() on the buffer, leaving the async read to write into a freed page. zrambvecreadpartial() was switched to NULL in commit 4e3c87b9421d ("zram: fix synchronous reads") for the same reason; the writepartial counterpart was missed.