On 1/23/2024 8:25 AM, Sohil Mehta wrote: > On 1/18/2024 11:30 PM, Hou Tao wrote: > >> vsyscall page could be disabled by CONFIG_LEGACY_VSYSCALL_NONE or >> vsyscall=none boot cmd-line, but it doesn't affect the reproduce of the >> problem and the returned error codes. >> > With vsyscall=emulate a direct read of the vsyscall address from > userspace is expected to go through. This is mode deprecated so maybe it > wouldn't matter much. Without the fix in patch 2/3, do you see the same > behavior with vsyscall=emulate set in the cmdline? Er, I think it depends on whether or not SMAP [1] feature is available. When SMAP feature is enabled, even the vsyscall page is populated, reading the vsyscall page through bpf_read_kernel() will trigger a page fault and then oops. But when there is not SMAP, bpf_read_kernel() will succeed. So I think the test may need to be skipped if vsyscall_mode is emulate. [1]: https://en.wikipedia.org/wiki/Supervisor_Mode_Access_Prevention > > Sohil
