mirror of https://gitee.com/openkylin/linux.git
cda2eaa359
The kvmppc_hpte_page_shifts function decodes the actual and base page sizes for a HPTE, returning -1 if it doesn't recognize the page size encoding. This then gets used as a shift amount in various places, which is undefined behaviour. This was reported by Coverity. In fact this should never occur, since we should only get HPTEs in the HPT which have a recognized page size encoding. The only place where this might not be true is in the call to kvmppc_actual_pgsz() near the beginning of kvmppc_do_h_enter(), where we are validating the HPTE value passed in from the guest. So to fix this and eliminate the undefined behaviour, we make kvmppc_hpte_page_shifts return 0 for unrecognized page size encodings, and make kvmppc_actual_pgsz() detect that case and return 0 for the page size, which will then cause kvmppc_do_h_enter() to return an error and refuse to insert any HPTE with an unrecognized page size encoding. To ensure that we don't get undefined behaviour in compute_tlbie_rb(), we take the 4k page size path for any unrecognized page size encoding. This should never be hit in practice because it is only used on HPTE values which have previously been checked for having a recognized page size encoding. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> |
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