[PATCH v2] eal: fix unused memseg length

[Yang Ming]

Hi experts, is there any chance to review and accept this patch?

On 2025/1/2 16:58, Yang Ming wrote:
> Fix the issue where OS memory is mistakenly freed with rte_free
> by setting the length (len) of unused memseg to 0.
>
> When `eal_legacy_hugepage_init()` releases the VA space for
> unused memseg lists(MSLs), it does not reset MSLs' length to 0.
> As a result, `mlx5_mem_is_rte()` may incorrectly identify OS
> memory as rte memory.
> This can lead to `mlx_free()` calling `rte_free()` on OS memory,
> causing an "EAL: Error: Invalid memory" log and failing to free
> the OS memory.
>
> This issue is occasional and occurs when the DPDK program’s
> memory map places the heap address range between 0 and len(32G).
> In such cases, malloc may return an address less than len,
> causing `mlx5_mem_is_rte()` to incorrectly treat it as rte
> memory.
>
> Also, consider how the MSL with `base_va == NULL` ends up in
> `mlx5_mem_is_rte()`. It comes from `rte_mem_virt2memseg_list()`
> which iterates MSLs and checks that an address belongs to
> [`base_va`; `base_va+len`) without checking whether
> `base_va == NULL` i.e. that the MSL is inactive. So this patch
> also corrects `rte_mem_virt2memseg_list()` behavior.
>
> Fixes: 66cc45e293ed ("mem: replace memseg with memseg lists")
> Cc: anatoly.burakov at intel.com
> Cc: stable at dpdk.org
>
> Signed-off-by: Yang Ming <ming.1.yang at nokia-sbell.com>
> Acked-by: Dmitry Kozlyuk <dmitry.kozliuk at gmail.com>
> ---
>   lib/eal/linux/eal_memory.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
> index 45879ca743..9dda60c0e1 100644
> --- a/lib/eal/linux/eal_memory.c
> +++ b/lib/eal/linux/eal_memory.c
> @@ -1472,6 +1472,7 @@ eal_legacy_hugepage_init(void)
>   		mem_sz = msl->len;
>   		munmap(msl->base_va, mem_sz);
>   		msl->base_va = NULL;
> +		msl->len = 0;
>   		msl->heap = 0;
>   
>   		/* destroy backing fbarray */