Re: [PATCH for-8.1 v2 2/2] target/mips: Avoid shift by negative number in page_table_walk_refill()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 17/7/23 23:35, Philippe Mathieu-Daudé wrote:

Oops, invalid authorship, this should be:

From: Peter Maydell <peter.maydell@linaro.org>

> Coverity points out that in page_table_walk_refill() we can shift by
> a negative number, which is undefined behaviour (CID 1452918,
> 1452920, 1452922).  We already catch the negative directory_shift and
> leaf_shift as being a "bail out early" case, but not until we've
> already used them to calculated some offset values.
> 
> Move the calculation of the offset values to after we've done the
> "return early if ptew > 1" check.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> [PMD: Check for ptew > 1, use unsigned type]
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   target/mips/tcg/sysemu/tlb_helper.c | 32 +++++++++++++++--------------
>   1 file changed, 17 insertions(+), 15 deletions(-)