CVE-2025-39715

In the Linux kernel, the following vulnerability has been resolved:

parisc: Revise gateway LWS calls to probe user read access

We use load and stbys,e instructions to trigger memory reference

interruptions without writing to memory. Because of the way read

access support is implemented, read access interruptions are only

triggered at privilege levels 2 and 3. The kernel and gateway

page execute at privilege level 0, so this code never triggers

a read access interruption. Thus, it is currently possible for

user code to execute a LWS compare and swap operation at an

address that is read protected at privilege level 3 (PRIV_USER).

Fix this by probing read access rights at privilege level 3 and

branching to lws_fault if access isn't allowed.