Re: [PATCH 1/2] KASan: test_kasan: hide buggy accesses from compiler

[Sascha Hauer <sha@pengutronix.de>]

On Thu, Nov 09, 2023 at 12:38:06PM +0100, Ahmad Fatoum wrote:
> Once we add __alloc_size attributes to allocations, GCC will complain
> about violation of memory safety in test_kasan.c.
> 
> That memory violation is intended though as test_kasan is meant to
> trigger kasan at runtime to verify correct operation.
> 
> Silence the warnings by hiding the origin of ptr, so the compiler loses
> context about the size of the allocation.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  lib/kasan/test_kasan.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)

Applied, thanks

Sascha

> 
> diff --git a/lib/kasan/test_kasan.c b/lib/kasan/test_kasan.c
> index 14511cdb80bd..a74251a6d9ad 100644
> --- a/lib/kasan/test_kasan.c
> +++ b/lib/kasan/test_kasan.c
> @@ -38,6 +38,8 @@ static noinline void malloc_oob_right(void)
>  		return;
>  	}
>  
> +	OPTIMIZER_HIDE_VAR(ptr);
> +
>  	ptr[size] = 'x';
>  
>  	free(ptr);
> @@ -55,6 +57,8 @@ static noinline void malloc_oob_left(void)
>  		return;
>  	}
>  
> +	OPTIMIZER_HIDE_VAR(ptr);
> +
>  	*ptr = *(ptr - 1);
>  	free(ptr);
>  }
> @@ -75,6 +79,8 @@ static noinline void malloc_oob_realloc_more(void)
>  		return;
>  	}
>  
> +	OPTIMIZER_HIDE_VAR(ptr2);
> +
>  	ptr2[size2] = 'x';
>  
>  	free(ptr2);
> @@ -95,6 +101,8 @@ static noinline void malloc_oob_realloc_less(void)
>  		return;
>  	}
>  
> +	OPTIMIZER_HIDE_VAR(ptr2);
> +
>  	ptr2[size2] = 'x';
>  
>  	free(ptr2);
> @@ -115,6 +123,9 @@ static noinline void malloc_oob_16(void)
>  		free(ptr2);
>  		return;
>  	}
> +
> +	OPTIMIZER_HIDE_VAR(ptr1);
> +
>  	*ptr1 = *ptr2;
>  	free(ptr1);
>  	free(ptr2);
> -- 
> 2.39.2
> 
> 
> 

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