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    Subject[PATCH v1 3/5] powerpc/fault: Reorder tests in bad_kernel_fault()
    Date
    Check address earlier to simplify the following test.

    Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    ---
    arch/powerpc/mm/fault.c | 10 +++++-----
    1 file changed, 5 insertions(+), 5 deletions(-)

    diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
    index 9ef9ee244f72..525e0c2b5406 100644
    --- a/arch/powerpc/mm/fault.c
    +++ b/arch/powerpc/mm/fault.c
    @@ -210,17 +210,17 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
    return true;
    }

    - if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) &&
    + // Kernel fault on kernel address is bad
    + if (address >= TASK_SIZE)
    + return true;
    +
    + if (!is_exec && (error_code & DSISR_PROTFAULT) &&
    !search_exception_tables(regs->nip)) {
    pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
    address,
    from_kuid(&init_user_ns, current_uid()));
    }

    - // Kernel fault on kernel address is bad
    - if (address >= TASK_SIZE)
    - return true;
    -
    // Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad
    if (!search_exception_tables(regs->nip))
    return true;
    --
    2.25.0
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