[PATCH] riscv: Fix a number of free'd resources in init_resources()

[PATCH] riscv: Fix a number of free'd resources in init_resources()

[Petr Pavlu]

Function init_resources() allocates a boot memory block to hold an array of
resources which it adds to iomem_resource. The array is filled in from its
end and the function then attempts to free any unused memory at the
beginning. The problem is that size of the unused memory is incorrectly
calculated and this can result in releasing memory which is in use by
active resources. Their data then gets corrupted later when the memory is
reused by a different part of the system.

Fix the size of the released memory to correctly match the number of unused
resource entries.

Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
 arch/riscv/kernel/setup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 18bd0e4bc36c..120b2f6f71bc 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -229,8 +229,8 @@ static void __init init_resources(void)
 	}
 
 	/* Clean-up any unused pre-allocated resources */
-	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
-	memblock_free(__pa(mem_res), mem_res_sz);
+	if (res_idx >= 0)
+		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
 	return;
 
  error:
-- 
2.32.0


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Re: [PATCH] riscv: Fix a number of free'd resources in init_resources()

[Nick Kossifidis]

Στις 2021-08-07 20:54, Petr Pavlu έγραψε:
> Function init_resources() allocates a boot memory block to hold an 
> array of
> resources which it adds to iomem_resource. The array is filled in from 
> its
> end and the function then attempts to free any unused memory at the
> beginning. The problem is that size of the unused memory is incorrectly
> calculated and this can result in releasing memory which is in use by
> active resources. Their data then gets corrupted later when the memory 
> is
> reused by a different part of the system.
> 
> Fix the size of the released memory to correctly match the number of 
> unused
> resource entries.
> 
> Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()")
> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> ---
>  arch/riscv/kernel/setup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 18bd0e4bc36c..120b2f6f71bc 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -229,8 +229,8 @@ static void __init init_resources(void)
>  	}
> 
>  	/* Clean-up any unused pre-allocated resources */
> -	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
> -	memblock_free(__pa(mem_res), mem_res_sz);
> +	if (res_idx >= 0)
> +		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
>  	return;
> 
>   error:

Ouch! Thanks for the fix.

Acked-by: Nick Kossifidis <mick@ics.forth.gr>

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Re: [PATCH] riscv: Fix a number of free'd resources in init_resources()

[Sunil V L]

On Sat, Aug 07, 2021 at 07:54:50PM +0200, Petr Pavlu wrote:
> Function init_resources() allocates a boot memory block to hold an array of
> resources which it adds to iomem_resource. The array is filled in from its
> end and the function then attempts to free any unused memory at the
> beginning. The problem is that size of the unused memory is incorrectly
> calculated and this can result in releasing memory which is in use by
> active resources. Their data then gets corrupted later when the memory is
> reused by a different part of the system.
> 
> Fix the size of the released memory to correctly match the number of unused
> resource entries.
> 
> Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()")
> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> ---
>  arch/riscv/kernel/setup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 18bd0e4bc36c..120b2f6f71bc 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -229,8 +229,8 @@ static void __init init_resources(void)
>  	}
>  
>  	/* Clean-up any unused pre-allocated resources */
> -	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
> -	memblock_free(__pa(mem_res), mem_res_sz);
> +	if (res_idx >= 0)
> +		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
>  	return;
>  
>   error:
I encountered this corruption and your patch came in time. 

Thank you very much!

Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Tested-by: Sunil V L <sunilvl@ventanamicro.com>

> -- 
> 2.32.0
> 
> 
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> linux-riscv@lists.infradead.org
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Re: [PATCH] riscv: Fix a number of free'd resources in init_resources()

[Palmer Dabbelt]

On Sat, 07 Aug 2021 10:54:50 PDT (-0700), petr.pavlu@suse.com wrote:
> Function init_resources() allocates a boot memory block to hold an array of
> resources which it adds to iomem_resource. The array is filled in from its
> end and the function then attempts to free any unused memory at the
> beginning. The problem is that size of the unused memory is incorrectly
> calculated and this can result in releasing memory which is in use by
> active resources. Their data then gets corrupted later when the memory is
> reused by a different part of the system.
>
> Fix the size of the released memory to correctly match the number of unused
> resource entries.
>
> Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()")
> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> ---
>  arch/riscv/kernel/setup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 18bd0e4bc36c..120b2f6f71bc 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -229,8 +229,8 @@ static void __init init_resources(void)
>  	}
>
>  	/* Clean-up any unused pre-allocated resources */
> -	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
> -	memblock_free(__pa(mem_res), mem_res_sz);
> +	if (res_idx >= 0)
> +		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
>  	return;
>
>   error:

Thanks, this is on fixes.

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