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The vstate in thread_struct is zeroed when the vector context is initialized. That includes read-only register vlenb, which holds the vector register length in bytes. Zeroed state persists until mstatus.VS becomes 'dirty' and a context switch saves the actual hardware values. This can expose the zero vlenb value to the user-space in early debug scenarios, e.g. when ptrace attaches to a traced process early, before any vector instruction except the first one was executed. Fix this by specifying proper vlenb on vector context init. Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com> Reviewed-by: Andy Chiu <andybnac@gmail.com> Tested-by: Andy Chiu <andybnac@gmail.com> Link: https://patch.msgid.link/20251214163537.1054292-3-geomatsi@gmail.com Signed-off-by: Paul Walmsley <pjw@kernel.org>