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    Subject[PATCH AUTOSEL 4.19 212/258] powerpc/mm: Fix reporting of kernel execute faults on the 8xx
    Date
    From: Christophe Leroy <christophe.leroy@c-s.fr>

    [ Upstream commit ffca395b11c4a5a6df6d6345f794b0e3d578e2d0 ]

    On the 8xx, no-execute is set via PPP bits in the PTE. Therefore
    a no-exec fault generates DSISR_PROTFAULT error bits,
    not DSISR_NOEXEC_OR_G.

    This patch adds DSISR_PROTFAULT in the test mask.

    Fixes: d3ca587404b3 ("powerpc/mm: Fix reporting of kernel execute faults")
    Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/mm/fault.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
    index d51cf5f4e45e..365526ee29b8 100644
    --- a/arch/powerpc/mm/fault.c
    +++ b/arch/powerpc/mm/fault.c
    @@ -221,7 +221,9 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
    static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
    unsigned long address)
    {
    - if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
    + /* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
    + if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
    + DSISR_PROTFAULT))) {
    printk_ratelimited(KERN_CRIT "kernel tried to execute"
    " exec-protected page (%lx) -"
    "exploit attempt? (uid: %d)\n",
    --
    2.19.1
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