Re: [PATCH v2 08/11] malloc: check result of rte_mem_virt2memseg

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2022-11-21 17:32 (UTC-0500), okaya@kernel.org:
> From: Sinan Kaya <okaya@kernel.org>
> 
> In malloc_elem_find_max_iova_contig result of call to rte_mem_virt2memseg
> is dereferenced here and may be null.
> 
> Signed-off-by: Sinan Kaya <okaya@kernel.org>
> ---
>  lib/eal/common/malloc_elem.c | 11 ++++++++---
>  lib/eal/common/malloc_heap.c |  2 +-
>  2 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/eal/common/malloc_elem.c b/lib/eal/common/malloc_elem.c
> index 83f05497cc..8f49812846 100644
> --- a/lib/eal/common/malloc_elem.c
> +++ b/lib/eal/common/malloc_elem.c
> @@ -63,6 +63,8 @@ malloc_elem_find_max_iova_contig(struct malloc_elem *elem, size_t align)
>  
>  	cur_page = RTE_PTR_ALIGN_FLOOR(contig_seg_start, page_sz);
>  	ms = rte_mem_virt2memseg(cur_page, elem->msl);
> +	if (ms == NULL)
> +		return 0;
>  
>  	/* do first iteration outside the loop */
>  	page_end = RTE_PTR_ADD(cur_page, page_sz);
> @@ -91,9 +93,12 @@ malloc_elem_find_max_iova_contig(struct malloc_elem *elem, size_t align)
>  			 * we're not blowing past data end.
>  			 */
>  			ms = rte_mem_virt2memseg(contig_seg_start, elem->msl);
> -			cur_page = ms->addr;
> -			/* don't trigger another recalculation */
> -			expected_iova = ms->iova;
> +			if (ms != NULL) {
> +				cur_page = ms->addr;
> +
> +				/* don't trigger another recalculation */
> +				expected_iova = ms->iova;
> +			}
>  			continue;
>  		}
>  		/* cur_seg_end ends on a page boundary or on data end. if we're
> diff --git a/lib/eal/common/malloc_heap.c b/lib/eal/common/malloc_heap.c
> index 3f41430e42..88270ce4d2 100644
> --- a/lib/eal/common/malloc_heap.c
> +++ b/lib/eal/common/malloc_heap.c
> @@ -930,7 +930,7 @@ malloc_heap_free(struct malloc_elem *elem)
>  		const struct rte_memseg *tmp =
>  				rte_mem_virt2memseg(aligned_start, msl);
>  
> -		if (tmp->flags & RTE_MEMSEG_FLAG_DO_NOT_FREE) {
> +		if ((tmp != NULL) && (tmp->flags & RTE_MEMSEG_FLAG_DO_NOT_FREE)) {
>  			/* this is an unfreeable segment, so move start */
>  			aligned_start = RTE_PTR_ADD(tmp->addr, tmp->len);
>  		}

In these three places "ms" or "tmp" are from the MSL by construction.
I think RTE_ASSERT() would be sufficient.