Re: [PATCH v2 1/2] RAS: Fix inverted context info bounds check in ARM processor errors

[Hanjun Guo]

Hi Abbott,

On 2026/8/25 21:43, Abbott Liu wrote:
> Commit 87880af2d24e ("APEI/GHES: ARM processor Error: don't go past
> allocated memory") added bounds checks for malformed ARM processor
> error records but contained a bug:
>
>    In log_arm_hw_error(), the ctx_info bounds check is inverted. The
>    condition `sz + (long)ctx_info - (long)err >= err->section_length`
>    adds ctx_info->size when the context header is already past the end
>    of the section instead of when it is within bounds. So change the
>    comparison to <=.
>
> Fixes: 87880af2d24e ("APEI/GHES: ARM processor Error: don't go past allocated memory")

This empty line is not needed.

> Signed-off-by: Abbott Liu <liuwenliang@xxxxxxxxxx>
> ---
>   drivers/ras/ras.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/ras/ras.c b/drivers/ras/ras.c
> index 03df3db62334..2540538a16a8 100644
> --- a/drivers/ras/ras.c
> +++ b/drivers/ras/ras.c
> @@ -74,7 +74,7 @@ void log_arm_hw_error(struct cper_sec_proc_arm *err, const u8 sev)
>   	for (n = 0; n < err->context_info_num; n++) {
>   		sz = sizeof(struct cper_arm_ctx_info);
>   
> -		if (sz + (long)ctx_info - (long)err >= err->section_length)
> +		if (sz + (long)ctx_info - (long)err <= err->section_length)
>   			sz += ctx_info->size;

sz is an int and ctx_info->size is u32, if ctx_info->size is big enough
for example over 0x7fffffff, the sz will be negative.

>   
>   		ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);

if the sz is negative, the ctx_info may pointer to a wrong place.

ctx_info->size will not over 0x7fffffff in practical but should we
consider the overflows?

Thanks
Hanjun

>