Re: [dpdk-stable] [PATCH v5] net/i40e: fix the core dump risk of wild pointer operation

[Jeff Guo <jia.guo@intel.com>]

On 5/18/2020 4:00 PM, Wei Zhao wrote:
> In i40e PMD code of function i40e_res_pool_free(), if valid_entry
> is freed by "rte_free(valid_entry);" in the code, then the following
> code for pool update may still use the wild pointer "valid_entry"
> for pool info update. It seems has the risk of core dump for
> using wild pointer operation, we should avoid this risk.
>
> Cc: stable@dpdk.org
> Fixes: 4861cde46116 ("i40e: new poll mode driver")
>
> Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
>
> ---
>
> v2:
> update commit log
>
> v3:
> set free pointer to NULL
>
> v4:
> change code style
>
> v5:
> fix an issue in v4
> ---
>   drivers/net/i40e/i40e_ethdev.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> index 749d85f54..00bb05179 100644
> --- a/drivers/net/i40e/i40e_ethdev.c
> +++ b/drivers/net/i40e/i40e_ethdev.c
> @@ -4935,6 +4935,7 @@ i40e_res_pool_free(struct i40e_res_pool_info *pool,
>   {
>   	struct pool_entry *entry, *next, *prev, *valid_entry = NULL;
>   	uint32_t pool_offset;
> +	uint16_t len;
>   	int insert;
>   
>   	if (pool == NULL) {
> @@ -4973,12 +4974,13 @@ i40e_res_pool_free(struct i40e_res_pool_info *pool,
>   	}
>   
>   	insert = 0;
> +	len = valid_entry->len;
>   	/* Try to merge with next one*/
>   	if (next != NULL) {
>   		/* Merge with next one */
> -		if (valid_entry->base + valid_entry->len == next->base) {
> +		if (valid_entry->base + len == next->base) {
>   			next->base = valid_entry->base;
> -			next->len += valid_entry->len;
> +			next->len += len;
>   			rte_free(valid_entry);
>   			valid_entry = next;
>   			insert = 1;
> @@ -4988,13 +4990,15 @@ i40e_res_pool_free(struct i40e_res_pool_info *pool,
>   	if (prev != NULL) {
>   		/* Merge with previous one */
>   		if (prev->base + prev->len == valid_entry->base) {
> -			prev->len += valid_entry->len;
> +			prev->len += len;
>   			/* If it merge with next one, remove next node */
>   			if (insert == 1) {
>   				LIST_REMOVE(valid_entry, next);
>   				rte_free(valid_entry);
> +				valid_entry = NULL;
>   			} else {
>   				rte_free(valid_entry);
> +				valid_entry = NULL;
>   				insert = 1;
>   			}
>   		}
> @@ -5010,8 +5014,8 @@ i40e_res_pool_free(struct i40e_res_pool_info *pool,
>   			LIST_INSERT_HEAD(&pool->free_list, valid_entry, next);
>   	}
>   
> -	pool->num_free += valid_entry->len;
> -	pool->num_alloc -= valid_entry->len;
> +	pool->num_free += len;
> +	pool->num_alloc -= len;
>   
>   	return 0;
>   }
Reviewed-by: Jeff Guo <jia.guo@intel.com>