Re: [PATCH -fixes v2] riscv: Fix wrong usage of lm_alias() when splitting a huge linear mapping

[Charlie Jenkins <charlie@rivosinc.com>]

On Tue, Dec 12, 2023 at 08:54:00PM +0100, Alexandre Ghiti wrote:
> lm_alias() can only be used on kernel mappings since it explicitly uses
> __pa_symbol(), so simply fix this by checking where the address belongs
> to before.
> 
> Fixes: 311cd2f6e253 ("riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings")
> Reported-by: syzbot+afb726d49f84c8d95ee1@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/linux-riscv/000000000000620dd0060c02c5e1@google.com/
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> ---
> 
> Changes in v2:
> - Fix llvm warning about unitialized return value
> 
>  arch/riscv/mm/pageattr.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> index fc5fc4f785c4..96cbda683936 100644
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -305,8 +305,13 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
>  				goto unlock;
>  		}
>  	} else if (is_kernel_mapping(start) || is_linear_mapping(start)) {
> -		lm_start = (unsigned long)lm_alias(start);
> -		lm_end = (unsigned long)lm_alias(end);
> +		if (is_kernel_mapping(start)) {
> +			lm_start = (unsigned long)lm_alias(start);
> +			lm_end = (unsigned long)lm_alias(end);
> +		} else {
> +			lm_start = start;
> +			lm_end = end;
> +		}
>  
>  		ret = split_linear_mapping(lm_start, lm_end);
>  		if (ret)
> -- 
> 2.39.2

Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>

> 
> 
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