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    Subject[PATCH AUTOSEL 4.14 060/108] powerpc/pseries/ras: Fix FWNMI_VALID off by one
    Date
    From: Nicholas Piggin <npiggin@gmail.com>

    [ Upstream commit deb70f7a35a22dffa55b2c3aac71bc6fb0f486ce ]

    This was discovered developing qemu fwnmi sreset support. This
    off-by-one bug means the last 16 bytes of the rtas area can not
    be used for a 16 byte save area.

    It's not a serious bug, and QEMU implementation has to retain a
    workaround for old kernels, but it's good to tighten it.

    Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
    Link: https://lore.kernel.org/r/20200508043408.886394-7-npiggin@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/platforms/pseries/ras.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
    index 99d1152ae224..5ec935521204 100644
    --- a/arch/powerpc/platforms/pseries/ras.c
    +++ b/arch/powerpc/platforms/pseries/ras.c
    @@ -325,10 +325,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
    /*
    * Some versions of FWNMI place the buffer inside the 4kB page starting at
    * 0x7000. Other versions place it inside the rtas buffer. We check both.
    + * Minimum size of the buffer is 16 bytes.
    */
    #define VALID_FWNMI_BUFFER(A) \
    - ((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
    - (((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
    + ((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
    + (((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))

    /*
    * Get the error information for errors coming through the
    --
    2.25.1
    \
     
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